HCN4

Summary

HCN4 (hyperpolarization activated cyclic nucleotide gated potassium channel 4, HGNC:16882) is a protein-coding gene on chromosome 15q24.1, encoding Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 4 (Q9Y3Q4). Hyperpolarization-activated ion channel that are permeable to Na(+) and K(+) ions with very slow activation and inactivation.

This gene encodes a member of the hyperpolarization-activated cyclic nucleotide-gated potassium channels. The encoded protein shows slow kinetics of activation and inactivation, and is necessary for the cardiac pacemaking process. This channel may also mediate responses to sour stimuli. Mutations in this gene have been linked to sick sinus syndrome 2, also known as atrial fibrillation with bradyarrhythmia or familial sinus bradycardia. Two pseudogenes have been identified on chromosome 15.

Source: NCBI Gene 10021 — RefSeq curated summary.

At a glance

• Gene–disease (curated): sick sinus syndrome 2, autosomal dominant (Definitive, ClinGen) — +3 more curated relationships
• GWAS associations: 29
• Clinical variants (ClinVar): 2,233 total — 8 pathogenic, 8 likely-pathogenic
• Phenotypes (HPO): 41
• Druggable target: yes — 2 molecules with ChEMBL bioactivity
• MANE Select transcript: NM_005477

Identifiers

Gene identifiers

Field	Value
HGNC ID	HGNC:16882
Approved symbol	HCN4
Name	hyperpolarization activated cyclic nucleotide gated potassium channel 4
Location	15q24.1
Locus type	gene with protein product
Status	Approved
Ensembl gene	ENSG00000138622
Ensembl biotype	protein_coding
OMIM	605206
Entrez	10021

Gene structure

Transcript identifiers

Ensembl transcripts: 1 — 1 protein_coding

ENST00000261917

RefSeq mRNA: 1 — MANE Select: NM_005477 NM_005477

CCDS: CCDS10248

Canonical transcript exons

ENST00000261917 — 8 exons

Exon	Start	End
ENSE00000885626	73319859	73323949
ENSE00000885629	73343385	73343808
ENSE00000885630	73367486	73368958
ENSE00001714815	73329573	73329791
ENSE00001752368	73324955	73325195
ENSE00002442566	73325298	73325444
ENSE00002495071	73332131	73332292
ENSE00002498480	73324089	73324253

Expression profiles

Bgee: expression breadth broad, 86 present calls, max score 79.37.

FANTOM5 (CAGE): breadth tissue_specific, TPM avg 0.3527 / max 29.8457, expressed in 176 samples.

FANTOM5 promoters (3 alternative TSS)

Promoter ID	TPM avg	Samples expressed
150845	0.2381	141
150847	0.0747	30
150846	0.0400	20

Top tissues by expression

231 total, by Bgee expression score (0-100, higher = more expressed):

Tissue	Anatomy ID	Expression score	Quality
tibialis anterior	UBERON:0001385	79.37	gold quality
right atrium auricular region	UBERON:0006631	78.72	gold quality
cardiac atrium	UBERON:0002081	78.55	gold quality
apex of heart	UBERON:0002098	76.61	gold quality
cortical plate	UBERON:0005343	75.59	gold quality
male germ line stem cell (sensu Vertebrata) in testis	CL:0000089 ∩ UBERON:0000473	74.17	gold quality
heart left ventricle	UBERON:0002084	73.16	gold quality
cardiac ventricle	UBERON:0002082	73.04	gold quality
secondary oocyte	CL:0000655	72.91	gold quality
heart right ventricle	UBERON:0002080	72.31	silver quality
primordial germ cell in gonad	CL:0000670 ∩ UBERON:0000991	72.01	gold quality
ileal mucosa	UBERON:0000331	70.10	gold quality
right testis	UBERON:0004534	70.05	gold quality
left testis	UBERON:0004533	69.72	gold quality
heart	UBERON:0000948	69.62	gold quality
islet of Langerhans	UBERON:0000006	68.78	gold quality
pancreatic ductal cell	CL:0002079	68.49	silver quality
testis	UBERON:0000473	68.11	gold quality
kidney epithelium	UBERON:0004819	66.50	gold quality
ventricular zone	UBERON:0003053	64.63	gold quality
superficial temporal artery	UBERON:0001614	63.79	gold quality
ganglionic eminence	UBERON:0004023	63.74	gold quality
oocyte	CL:0000023	63.42	silver quality
deltoid	UBERON:0001476	63.30	silver quality
lateral nuclear group of thalamus	UBERON:0002736	62.33	gold quality
amniotic fluid	UBERON:0000173	61.58	gold quality
vena cava	UBERON:0004087	61.50	silver quality
esophagus squamous epithelium	UBERON:0006920	60.72	gold quality
endometrium epithelium	UBERON:0004811	60.65	gold quality
quadriceps femoris	UBERON:0001377	59.87	gold quality

Single-cell (SCXA)

Detected in 1 experiment(s), a significant marker in 0.

Experiment	Marker?	Max mean expression
E-ANND-3	no	0.79

Regulation

Is transcription factor: no

Upstream regulators (CollecTRI, top): AR, GATA6, MEF2A, MEF2C, NKX2-5, REST, SP1, TBX3, THRB

miRNA regulators (miRDB)

118 targeting HCN4, top 30 by miRDB confidence (max_score; target_count = how many genes the miRNA targets in total — lower means more specific):

miRNA	Max score	Avg score	miRNA target_count
HSA-MIR-6867-5P	100.00	82.21	3464
HSA-MIR-1252-5P	100.00	69.80	2774
HSA-MIR-3163	100.00	77.23	8605
HSA-MIR-4533	100.00	69.48	2758
HSA-MIR-5692A	100.00	74.40	6850
HSA-MIR-4747-5P	100.00	67.90	2681
HSA-MIR-5196-5P	100.00	67.98	2761
HSA-MIR-4455	100.00	65.48	1587
HSA-MIR-126-5P	100.00	72.71	3180
HSA-MIR-6833-3P	100.00	70.63	3197
HSA-MIR-4768-5P	100.00	69.49	2861
HSA-MIR-3667-3P	99.99	67.17	1636
HSA-MIR-3662	99.99	73.82	5684
HSA-MIR-27A-3P	99.98	72.13	2955
HSA-MIR-27B-3P	99.98	72.13	2955
HSA-MIR-9985	99.98	72.11	2939
HSA-MIR-512-3P	99.97	67.35	1049
HSA-MIR-6778-3P	99.96	67.29	2693
HSA-MIR-128-3P	99.95	71.17	2484
HSA-MIR-216A-3P	99.95	71.19	2505
HSA-MIR-106A-5P	99.90	73.94	2683
HSA-MIR-548E-5P	99.89	72.73	4486
HSA-MIR-17-5P	99.89	73.83	2665
HSA-MIR-3681-3P	99.88	70.46	2254
HSA-MIR-106B-5P	99.88	74.72	2795
HSA-MIR-20A-5P	99.88	74.76	2769
HSA-MIR-20B-5P	99.88	74.01	2621
HSA-MIR-519D-3P	99.88	73.97	2607
HSA-MIR-526B-3P	99.88	74.06	2587
HSA-MIR-93-5P	99.88	73.98	2606

Literature-anchored findings (GeneRIF, showing 40)

• The rat HCN1 and HCN4 were shown to mediate responses to sour stimuli, suggesting a potential new function for the related human proteins. (PMID:11675786)
• HCN4 activates substantially slower than HCN2 and with a half-maximum activation voltage approximately equal 10 mV less negative, both isoforms activate more positively in myocytes suggesting cell-type specificity (PMID:12194012)
• A heterozygous 1-bp deletion (1631delC) in exon 5 of the human HCN4 gene was detected in a patient with idiopathic sinus bradycardia and chronotropic incompetence (PMID:12750403)
• the speed of activation of the HCN4 channel is determined by structural elements present in the S1, S1-S2 linker, and the S2 segment (PMID:12813043)
• co-expressed KCNE2 enhanced HCN4-generated current amplitudes, slowed the activation kinetics and shifted the voltage for half-maximal activation of currents to more negative voltages (PMID:12856183)
• A mouse model for a loss-of-function study of HCN4, which has a strong implication for the function of the related human protein. (PMID:14657344)
• Data suggest that the loss of function of HCN4 is associated with sinus nodal dysfunction. (PMID:15123648)
• Native I(f) channels in atrial myocardium are heteromeric complexes composed of HCN4 and/or HCN2. (PMID:15687126)
• Sinus bradycardia in members of a large family was associated with a mutation in the gene coding for the pacemaker HCN4 ion channel. (PMID:16407510)
• With computer modelling, we show that in channels with relatively slow opening kinetics and fast mode-shift transitions, such as HCN2 and HCN4 channels, the mode shift effects are not readily observable, except in the tail kinetics. (PMID:16777944)
• A missense mutation, G480R, in the ion channel pore domain caused sinus node dysfunction. Mutant HCN4 had reduced synthesis, was activated at more negative voltages, & had defective ion trafficking. (PMID:17646576)
• Src tyrosine kinase enhances HCN4 currents by shifting their activation to more positive potentials and increasing the whole cell channel conductance as well as speeding the channel kinetics. Tyr(531) mediates most of Src’s actions on HCN4 channels. (PMID:17977941)
• The HCN4 channel played a preventive role in triggering bradycardia-induced ventricular arrhythmias. (PMID:19165230)
• HCN4 associates with Cav3 to form a HCN4 macromolecular complex. Our results also indicated that disruption of caveolae using P104L alters HCN4 function and could cause a reduction of cardiac pacemaker activity. (PMID:19238754)
• These data reveal the pathophysiologic mechanism of hHCN4-573X-linked sinoatrial node dysfunction in humans. (PMID:19570998)
• novel mechanism using three endogenous Src kinases to rescue a trafficking defective HCN4 mutant channel (D553N) by enhancing the tyrosine phosphorylation of the mutant channel protein. (PMID:19748888)
• In this review, we focus on genotype-phenotype correlation of HCN4 mutations and discuss the relative contribution of various ion channels to sinus node function. (PMID:19796353)
• hHCN4 hysteresis potentially plays a crucial role in human sinoatrial node pacemaking activity. (PMID:20179882)
• Higher HCN4 mRNA levels in the hypertrophic cardiomyopathy hearts suggest that up-regulation of HCN4 gene expression might be responsible for ventricular arrhythmia that leads to sudden death. (PMID:20207172)
• A novel mutation is found in HCN4 gene causing symptoms of sinus bradycardia in unrelated male Moroccan Jews. (PMID:20662977)
• HCN4 channels are expressed in different patterns in brain and heart; the N terminus is important for HCN4 channel activation (PMID:21372143)
• These findings suggest HCN4 as a genetic susceptibility factor for mood and anxiety disorders (PMID:21529705)
• Genetic analysis in 48 Sudden unexpected death in epilepsy cases identified six novel and three previously reported nonsynonymous (amino acid changing) variants in HCN1 , HCN2, HCN3 and HCN4. (PMID:21615589)
• Data show that beta(2)-adrenergic receptors beta(2)ARs form protein complexes with the HCN4 channel, as well as with other subtypes of HCN channels. (PMID:22613709)
• Anti-HCN4 antibodies in the brain might contribute to the pathogenesis of tic symptoms in Tourette’s syndrome patients. (PMID:22683190)
• The HCN4 channels generate currents with reduced amplitude, while the kinetics of activation and deactivation are not altered. (PMID:23075627)
• Structural and functional description of the disease causing mutation in human HCN4. (PMID:23103389)
• data show a developmental change in HCN4-Cav3 association in human embryonic stem cell-derived cardiomyocytes (PMID:23311301)
• Genetic alterations in ion channels that regulate cardiac rhythms may account for some cases of SIDS, as demonstrated by this report of 2 potentially pathogenic novel or rare variants in the HCN4 gene. (PMID:23623143)
• Cardiomyogenic progenitors derived from the first heart field and human pluripotent stem cells express HCN4. (PMID:23974038)
• The HCN4-G1097W mutant channels displayed a loss-of-function type modulation on cardiac If channels and thus could predispose them to AV nodal dysfunction. These data provide a novel insight into the genetic basis for the AV block. (PMID:24492017)
• Here, we review the changes in expression and kinetics of HCN4 mutant channels and provide an overview of their effects on If during the time course of a human SAN action potential, both under resting conditions and upon adrenergic stimulation. [review] (PMID:24569893)
• study identified a novel trafficking-defective mutation in the amino-terminus of HCN4 channel in individuals with early-onset atrial fibrillation (AF); findings support that novel loss-of-function mutations in the HCN4 channel may increase susceptibility and have a role in AF pathogenesis (PMID:24607718)
• used NMR to probe the changes caused by the binding of cAMP and of cCMP, a partial agonist, to the apo-cAMP-binding domain of HCN4 (PMID:24878962)
• study establishes the role of f-channels in cardiac automaticity and indicates that arrhythmia related to HCN loss-of-function may be managed by pharmacological or genetic inhibition of GIRK4 channels (PMID:25144323)
• Mutations in ion channel gene HCN4 may be associated with structural abnormalities of the myocardium. (PMID:25145517)
• The symptom complex of sinus node dysfunction and noncompaction cardiomyopathy is associated with heritable HCN4 defects. (PMID:25145518)
• The study analyzed HCN4 intracellular region dynamics in the four states of the thermodynamic cycle arising from the coupling between cAMP binding and tetramerization equilibria. (PMID:25944904)
• Aged patients with sinus rhythm exhibited significantly higher expression levels of HCN2 and HCN4 channel mRNA and protein (P<0.05), but significantly lower expression levels of miR1 and 133, compared with those of adult patients with sinus rhythm. (PMID:26005035)
• Our results confirm the genetic evidence for the involvement of the HCN4 mutations in the combined bradycardia-non compaction cardiomyopathy phenotype and illustrates that. (PMID:26206080)

Cross-species orthologs

15 orthologs

Organism	Symbol	Gene ID
danio_rerio	hcn4	ENSDARG00000061685
danio_rerio	hcn4l	ENSDARG00000074419
mus_musculus	Hcn4	ENSMUSG00000032338
rattus_norvegicus	Hcn4	ENSRNOG00000009450
drosophila_melanogaster	sei	FBGN0003353
drosophila_melanogaster	Elk	FBGN0011589
drosophila_melanogaster	CG6026	FBGN0038676
drosophila_melanogaster	CngA	FBGN0261612
drosophila_melanogaster	Cngl	FBGN0263257
drosophila_melanogaster	CngB	FBGN0266346
caenorhabditis_elegans		WBGENE00000487
caenorhabditis_elegans	tax-2	WBGENE00006525
caenorhabditis_elegans		WBGENE00006526
caenorhabditis_elegans		WBGENE00006830
caenorhabditis_elegans		WBGENE00022295

Paralogs (17): KCNH2 (ENSG00000055118), CNGB1 (ENSG00000070729), KCNH4 (ENSG00000089558), HCN2 (ENSG00000099822), CNGA4 (ENSG00000132259), KCNH3 (ENSG00000135519), KCNH5 (ENSG00000140015), KCNH1 (ENSG00000143473), HCN3 (ENSG00000143630), CNGA3 (ENSG00000144191), HCN1 (ENSG00000164588), CNGB3 (ENSG00000170289), KCNH6 (ENSG00000173826), CNGA2 (ENSG00000183862), KCNH8 (ENSG00000183960), KCNH7 (ENSG00000184611), CNGA1 (ENSG00000198515)

Protein

Protein identifiers

Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 4 — Q9Y3Q4 (reviewed: Q9Y3Q4)

All UniProt accessions (1): Q9Y3Q4

UniProt curated annotations — full annotation on UniProt →

Function. Hyperpolarization-activated ion channel that are permeable to Na(+) and K(+) ions with very slow activation and inactivation. Exhibits higher selectivity for K(+) over Na(+) ions. Contributes to the native pacemaker currents in heart (If) that regulate the rhythm of heart beat. Contributes to the native pacemaker currents in neurons (Ih). May mediate responses to sour stimuli.

Subunit / interactions. Homotetramer (PubMed:20829353, PubMed:22006928, PubMed:24776929, Ref.10). The channel assemble into homotetramers or heteromeric complexes that contains of four pore-forming subunits. Interacts with PEX5L with a 4:4 HCN4:PEX5L stoichiometry; reduces the effects of cAMP on the voltage-dependence and rate of activation. Interacts with IRAG1; regulates HCN4 channel activity. Interacts with IRAG2; regulates HCN4 channel activity.

Subcellular location. Cell membrane.

Tissue specificity. Highly expressed in thalamus, testis and in heart, both in ventricle and atrium. Detected at much lower levels in amygdala, substantia nigra, cerebellum and hippocampus.

Post-translational modifications. S-palmitoylated.

Disease relevance. Sick sinus syndrome 2 (SSS2) [MIM:163800] The term ‘sick sinus syndrome’ encompasses a variety of conditions caused by sinus node dysfunction. The most common clinical manifestations are syncope, presyncope, dizziness, and fatigue. Electrocardiogram typically shows sinus bradycardia, sinus arrest, and/or sinoatrial block. Episodes of atrial tachycardias coexisting with sinus bradycardia (’tachycardia-bradycardia syndrome’) are also common in this disorder. SSS occurs most often in the elderly associated with underlying heart disease or previous cardiac surgery, but can also occur in the fetus, infant, or child without heart disease or other contributing factors. SSS2 onset is in utero or at birth. The disease is caused by variants affecting the gene represented in this entry. Brugada syndrome 8 (BRGDA8) [MIM:613123] A tachyarrhythmia characterized by right bundle branch block and ST segment elevation on an electrocardiogram (ECG). It can cause the ventricles to beat so fast that the blood is prevented from circulating efficiently in the body. When this situation occurs, the individual will faint and may die in a few minutes if the heart is not reset. The gene represented in this entry may be involved in disease pathogenesis. Epilepsy, idiopathic generalized 18 (EIG18) [MIM:619521] An autosomal dominant form of idiopathic generalized epilepsy, a disorder characterized by recurring generalized seizures in the absence of detectable brain lesions and/or metabolic abnormalities. Generalized seizures arise diffusely and simultaneously from both hemispheres of the brain. Seizure types include juvenile myoclonic seizures, absence seizures, and generalized tonic-clonic seizures. EIG18 is characterized by onset of myoclonic seizures in infancy. Although the seizures remit, some patients may have later speech or cognitive impairment. Disease susceptibility is associated with variants affecting the gene represented in this entry.

Activity regulation. Activated by cAMP and to a lesser extent by cGMP and cCMP. cAMP binding causes a conformation change that leads to the assembly of an active tetramer and channel opening. Binding of cAMP removes a tonic inhibition conferred by cyclic nucleotide-binding domain (CNBD) on channel opening. Cyclic dinucleotides can modulate HCN4 channel; cyclic dinucleotides acting as potent antagonists of cAMP. Inhibited by extracellular Cs(+) ions. Auxiliary subunits can also regulate HCN4 channel. IRAG1 causes a gain-of-function by shifting HCN4 activation to more depolarized membrane potentials in the absence of cAMP. In contrast, IRAG2 causes a loss-of-function by inhibiting cAMP-dependent potentiation of HCN4 activation.

Domain organisation. Contains six transmembrane segments (S1-S6) and an intervening P-loop. The segment S4 is the voltage-sensor and is characterized by a series of positively charged amino acids at every third position, while the S5-S6 segments together with the P-loop form a centrally located pore of the channel. Contains a cyclic nucleotide-binding domain (CNBD) in their C-terminal region. The CNBD is connected to the pore forming transmembrane segment via the C-linker. Contains a unique pocket located in the cytosolic C-terminal domain, identified as a likely binding site for di-cyclic nucleotides.

Similarity. Belongs to the potassium channel HCN family.

RefSeq proteins (1): NP_005468* (*=MANE)

Domains & families (InterPro)

ID	Name	Type
IPR000595	cNMP-bd_dom	Domain
IPR003938	K_chnl_volt-dep_EAG/ELK/ERG	Family
IPR005821	Ion_trans_dom	Domain
IPR013621	Ion_trans_N	Domain
IPR014710	RmlC-like_jellyroll	Homologous_superfamily
IPR018488	cNMP-bd_CS	Conserved_site
IPR018490	cNMP-bd_dom_sf	Homologous_superfamily
IPR051413	K/Na_HCN_channel	Family

Pfam: PF00027, PF00520, PF08412

Catalyzed reactions (Rhea), 2 shown:

• K(+)(in) = K(+)(out) (RHEA:29463)
• Na(+)(in) = Na(+)(out) (RHEA:34963)

UniProt features (100 total): helix 27, strand 14, compositionally biased region 11, binding site 11, topological domain 8, transmembrane region 6, region of interest 5, sequence variant 4, mutagenesis site 4, modified residue 3, turn 3, chain 1, intramembrane region 1, glycosylation site 1, sequence conflict 1

Structure

Experimental structures (PDB)

8 structures.

PDB	Method	Resolution (Å)
3OTF	X-RAY DIFFRACTION	2.4
3U11	X-RAY DIFFRACTION	2.5
4NVP	X-RAY DIFFRACTION	2.5
4HBN	X-RAY DIFFRACTION	2.6
4KL1	X-RAY DIFFRACTION	2.7
6GYN	ELECTRON MICROSCOPY	3.4
6GYO	ELECTRON MICROSCOPY	3.4
2MNG	SOLUTION NMR

Predicted structure (AlphaFold)

Model	pLDDT	Fraction very-high
AF-Q9Y3Q4-F1	61.86	0.28

Functional residue map

Curated UniProt residues grouped by drug-discovery relevance — catalytic, ligand-binding, modification, and mutation-validated positions. Source: UniProtKB sequence features.

Ligand- & substrate-binding residues (11): 559; 562; 564; 566; 659; 660; 662; 669; 670; 673; 710

Post-translational modifications (3): 138, 1105, 1108

Glycosylation sites (1): 458

Mutagenesis-validated functional residues (4):

Position	Phenotype
559	alters the channel response to c-di-gmp.
564	alters the channel response to c-di-gmp.
566	alters the channel response to c-di-gmp.
680	abolishes cyclic-dinucleotide modulation of hcn4 channels.

Function

Pathways and Gene Ontology

Reactome pathways

1 pathways

ID	Pathway
R-HSA-1296061	HCN channels

MSigDB gene sets: 259 (showing top): GOBP_POTASSIUM_ION_TRANSPORT, GOBP_MEMBRANE_DEPOLARIZATION, GOBP_RESPONSE_TO_NITROGEN_COMPOUND, GOBP_MUSCLE_TISSUE_DEVELOPMENT, BENPORATH_ES_WITH_H3K27ME3, GOBP_CIRCULATORY_SYSTEM_PROCESS, REACTOME_POTASSIUM_CHANNELS, GOBP_SODIUM_ION_TRANSMEMBRANE_TRANSPORT, GOBP_MEMBRANE_DEPOLARIZATION_DURING_ACTION_POTENTIAL, TGACCTY_ERR1_Q2, GOBP_REGULATION_OF_MEMBRANE_DEPOLARIZATION, RIZKI_TUMOR_INVASIVENESS_3D_DN, GGGTGGRR_PAX4_03, GOBP_CELLULAR_RESPONSE_TO_OXYGEN_CONTAINING_COMPOUND, SP1_Q2_01

GO Biological Process (25): regulation of heart rate (GO:0002027), sinoatrial node development (GO:0003163), regulation of membrane depolarization (GO:0003254), monoatomic cation transport (GO:0006812), muscle contraction (GO:0006936), blood circulation (GO:0008015), sodium ion transmembrane transport (GO:0035725), regulation of membrane potential (GO:0042391), regulation of cardiac muscle contraction (GO:0055117), cellular response to cAMP (GO:0071320), cellular response to cGMP (GO:0071321), potassium ion transmembrane transport (GO:0071805), membrane depolarization during cardiac muscle cell action potential (GO:0086012), SA node cell action potential (GO:0086015), membrane depolarization during SA node cell action potential (GO:0086046), regulation of heart rate by cardiac conduction (GO:0086091), sodium ion import across plasma membrane (GO:0098719), regulation of SA node cell action potential (GO:0098907), regulation of cardiac muscle cell action potential involved in regulation of contraction (GO:0098909), potassium ion import across plasma membrane (GO:1990573), monoatomic ion transport (GO:0006811), potassium ion transport (GO:0006813), sodium ion transport (GO:0006814), monoatomic ion transmembrane transport (GO:0034220), transmembrane transport (GO:0055085)

GO Molecular Function (11): intracellularly cAMP-activated cation channel activity (GO:0005222), voltage-gated sodium channel activity (GO:0005248), voltage-gated potassium channel activity (GO:0005249), cAMP binding (GO:0030552), identical protein binding (GO:0042802), voltage-gated potassium channel activity involved in SA node cell action potential depolarization (GO:0086041), nucleotide binding (GO:0000166), monoatomic ion channel activity (GO:0005216), potassium channel activity (GO:0005267), sodium channel activity (GO:0005272), protein binding (GO:0005515)

GO Cellular Component (7): plasma membrane (GO:0005886), axon (GO:0030424), dendrite (GO:0030425), perinuclear region of cytoplasm (GO:0048471), HCN channel complex (GO:0098855), membrane (GO:0016020), monoatomic ion channel complex (GO:0034702)

Reactome top-level categories

Rollup of top-1 pathways:

Category	Pathways
Potassium Channels	1

GO top-level categories

Rollup of top GO terms by namespace:

Category	Terms
cardiac muscle cell action potential	3
regulation of heart contraction	2
regulation of biological quality	2
monoatomic cation transmembrane transport	2
cellular response to nitrogen compound	2
cellular response to oxygen-containing compound	2
SA node cell action potential	2
inorganic cation import across plasma membrane	2
regulation of cardiac muscle cell action potential	2
monoatomic cation channel activity	2
neuron projection	2
cellular anatomical structure	2
cardiac conduction system development	1
atrial cardiac muscle tissue development	1
regulation of membrane potential	1
regulation of cellular process	1
membrane depolarization	1
monoatomic ion transport	1
muscle system process	1
circulatory system process	1
sodium ion transport	1
monoatomic ion transmembrane transport	1
regulation of striated muscle contraction	1
cardiac muscle contraction	1
response to cAMP	1
response to cGMP	1
potassium ion transport	1
membrane depolarization during action potential	1
SA node cell to atrial cardiac muscle cell signaling	1
membrane depolarization during cardiac muscle cell action potential	1
regulation of heart rate	1
cardiac conduction	1
sodium ion transmembrane transport	1
regulation of cell communication	1
regulation of cardiac muscle cell contraction	1
potassium ion transmembrane transport	1
intracellularly cyclic nucleotide-activated monoatomic cation channel activity	1
sodium channel activity	1
potassium channel activity	1
voltage-gated monoatomic cation channel activity	1

Protein interactions and networks

STRING

1202 interactions, top by confidence (×1000):

Protein A	Protein B	Partner UniProt	Score
HCN4	SCN5A	Q14524	950
HCN4	GJA5	P36382	871
HCN4	NKX2-5	P52952	858
HCN4	GPD1L	Q8N335	834
HCN4	CACNA1C	Q13936	827
HCN4	SCN1B	Q07699	826
HCN4	GJC1	P36383	823
HCN4	KCNE3	Q9Y6H6	823
HCN4	CACNB2	Q08289	803
HCN4	SCN3B	Q9NY72	799
HCN4	KCNE2	Q9Y6J6	766
HCN4	PITX2	Q99697	755
HCN4	SHOX2	O60902	741
HCN4	TBX18	O95935	738
HCN4	KCNJ2	P48049	735

IntAct

67 interactions, top by confidence:

A	B	Type	Score
	HCN4	psi-mi:“MI:0407”(direct interaction)	0.780

BioGRID (10): HCN4 (Affinity Capture-Western), HCN3 (Affinity Capture-Western), HCN2 (Affinity Capture-Western), HCN4 (Affinity Capture-Western), HCN4 (Affinity Capture-Western), HCN1 (Affinity Capture-Western), KCNE2 (Two-hybrid), HCN4 (Affinity Capture-MS), HCN2 (Affinity Capture-MS), HCN3 (Affinity Capture-MS)

ESM2 similar proteins: A2APX8, A6H8H5, G5EFJ9, O18868, O18965, O60741, O70507, O88703, O88704, O95259, P04774, P15387, P17970, P35498, P55934, P58391, P58392, Q00194, Q02280, Q03041, Q03611, Q03717, Q14721, Q16281, Q29441, Q4ZHA6, Q60603, Q62897, Q62927, Q63099, Q63472, Q8MJD7, Q8NCM2, Q90805, Q920E3, Q95167, Q9EPI9, Q9ER33, Q9JKA7, Q9JKA8

Diamond homologs: O60741, O70507, O88703, O88704, O88705, P05987, P07278, P31320, P36600, Q2K5E1, Q6BZG7, Q6CPK7, Q6FQL6, Q8MMZ8, Q98GN8, Q9JKA7, Q9JKA8, Q9JKA9, Q9JKB0, Q9MZS1, Q9P1Z3, Q9TV66, Q9UL51, Q9Y3Q4, P9WM60, P9WM61, Q03042, Q03043, A5K0N4, A0A509AKL0, A0R3F9, A3RL54, A8X6H1, O05581, O14448, O42794, O59922, O76360, O77676, P00514

SIGNOR signaling

1 interactions.

A	Effect	B	Mechanism
SRC	up-regulates	HCN4	phosphorylation

Disease & clinical

Clinical variants and AI predictions

ClinVar

2233 variants total. Per-class counts are floors (≥ shown; pagination cap):

Classification	Count (floor)
Pathogenic	8
Likely pathogenic	8
Uncertain significance	1237
Likely benign	812
Benign	55

Top pathogenic / likely-pathogenic (16)

Variant ID	HGVS	Classification
1697968	NM_005477.3(HCN4):c.1740G>C (p.Glu580Asp)	Pathogenic
374858	NM_005477.3(HCN4):c.1920_1932dup (p.Lys645fs)	Pathogenic
374859	NM_005477.3(HCN4):c.1444G>C (p.Gly482Arg)	Pathogenic
374861	NM_005477.3(HCN4):c.1241C>G (p.Ala414Gly)	Pathogenic
5173	NM_005477.3(HCN4):c.2016C>A (p.Ser672Arg)	Pathogenic
5174	NM_005477.3(HCN4):c.1631del (p.Pro544fs)	Pathogenic
5176	NM_005477.3(HCN4):c.1438G>C (p.Gly480Arg)	Pathogenic
571947	NM_005477.3(HCN4):c.1123C>T (p.Arg375Cys)	Pathogenic
1504964	NM_005477.3(HCN4):c.1442A>G (p.Tyr481Cys)	Likely pathogenic
1675065	NM_005477.3(HCN4):c.1445G>A (p.Gly482Glu)	Likely pathogenic
2028837	NM_005477.3(HCN4):c.2515_2518dup (p.Ala840fs)	Likely pathogenic
2636206	NM_005477.3(HCN4):c.1433G>A (p.Cys478Tyr)	Likely pathogenic
404118	NM_005477.3(HCN4):c.1439G>T (p.Gly480Val)	Likely pathogenic
470654	NM_005477.3(HCN4):c.2143+1G>A	Likely pathogenic
4755562	NM_005477.3(HCN4):c.1591-1861_2867del	Likely pathogenic
666148	NM_005477.3(HCN4):c.1471G>C (p.Asp491His)	Likely pathogenic

SpliceAI

1133 predictions. Top by Δscore:

Variant	Effect	Δscore
15:73323950:C:CA	acceptor_loss	1.0000
15:73323950:C:CC	acceptor_gain	1.0000
15:73323956:C:CT	acceptor_gain	1.0000
15:73323956:C:T	acceptor_gain	1.0000
15:73323958:C:CT	acceptor_gain	1.0000
15:73324083:CCTCA:C	donor_loss	1.0000
15:73324084:CTCAC:C	donor_loss	1.0000
15:73324085:TCA:T	donor_loss	1.0000
15:73324086:CACC:C	donor_loss	1.0000
15:73324087:ACC:A	donor_loss	1.0000
15:73324088:C:CG	donor_loss	1.0000
15:73324249:GATCT:G	acceptor_gain	1.0000
15:73324250:ATCT:A	acceptor_gain	1.0000
15:73324252:CT:C	acceptor_gain	1.0000
15:73324253:TCTGC:T	acceptor_loss	1.0000
15:73324254:C:CC	acceptor_gain	1.0000
15:73324254:CTGCC:C	acceptor_loss	1.0000
15:73324258:C:CT	acceptor_gain	1.0000
15:73324950:CTCA:C	donor_loss	1.0000
15:73324951:TCACC:T	donor_loss	1.0000
15:73324952:CACCT:C	donor_loss	1.0000
15:73324953:A:AC	donor_gain	1.0000
15:73324953:ACC:A	donor_loss	1.0000
15:73324953:ACCT:A	donor_gain	1.0000
15:73324954:C:CC	donor_gain	1.0000
15:73324954:CCT:C	donor_gain	1.0000
15:73324954:CCTC:C	donor_gain	1.0000
15:73324956:T:TA	donor_gain	1.0000
15:73325213:T:TC	acceptor_gain	1.0000
15:73325292:GCTCA:G	donor_loss	1.0000

AlphaMissense

7762 scored. Top likely-pathogenic:

Variant	Protein change	am_pathogenicity
15:73324094:C:G	R713P	1.000
15:73324100:A:G	L711P	1.000
15:73324100:A:T	L711Q	1.000
15:73324103:C:G	R710P	1.000
15:73324104:G:C	R710G	1.000
15:73324104:G:T	R710S	1.000
15:73324112:G:T	A707E	1.000
15:73324113:C:G	A707P	1.000
15:73324120:C:A	E704D	1.000
15:73324120:C:G	E704D	1.000
15:73324123:G:C	F703L	1.000
15:73324123:G:T	F703L	1.000
15:73324124:A:C	F703C	1.000
15:73324124:A:G	F703S	1.000
15:73324125:A:G	F703L	1.000
15:73324127:G:T	A702D	1.000
15:73324133:C:G	R700P	1.000
15:73324136:A:C	M699R	1.000
15:73324136:A:G	M699T	1.000
15:73324136:A:T	M699K	1.000
15:73324154:A:C	L693R	1.000
15:73324154:A:G	L693P	1.000
15:73324154:A:T	L693Q	1.000
15:73324165:G:C	F689L	1.000
15:73324165:G:T	F689L	1.000
15:73324166:A:C	F689C	1.000
15:73324166:A:G	F689S	1.000
15:73324167:A:G	F689L	1.000
15:73324181:A:G	L684P	1.000
15:73324181:A:T	L684Q	1.000

dbSNP variants (sampled 300 via entrez): RS1000038203 (15:73359827 G>A), RS1000114404 (15:73321737 G>A), RS1000146547 (15:73347336 T>C), RS1000217690 (15:73325406 G>T), RS1000280361 (15:73337108 T>C), RS1000321862 (15:73354357 C>T), RS1000356753 (15:73329174 A>C), RS1000372135 (15:73370845 G>A), RS1000434930 (15:73347582 G>A,C), RS1000492956 (15:73370090 GAC>G), RS1000497342 (15:73320293 A>AGTC), RS1000551642 (15:73364127 C>T), RS1000566379 (15:73324729 T>A), RS1000817007 (15:73369770 T>G), RS1000944614 (15:73353784 C>T)

Disease associations

OMIM: gene MIM:605206 | disease phenotypes: MIM:613123, MIM:163800, MIM:619521, MIM:604169, MIM:601144

GenCC curated gene-disease

Disease	Classification	Inheritance
sick sinus syndrome 2, autosomal dominant	Strong	Autosomal dominant
Brugada syndrome 8	Moderate	Autosomal dominant
familial sick sinus syndrome	Supportive	Autosomal dominant
Brugada syndrome 1	Disputed Evidence	Autosomal dominant

ClinGen Gene-Disease Validity (2)

Expert-panel classifications — Definitive > Strong > Moderate > Limited > Disputed > Refuted.

Disease	Classification	Inheritance
sick sinus syndrome 2, autosomal dominant	Definitive	AD
Brugada syndrome 1	Disputed	AD

Mondo (18): Brugada syndrome 8 (MONDO:0013148), sick sinus syndrome 2, autosomal dominant (MONDO:0008102), epilepsy, idiopathic generalized, susceptibility to, 18 (MONDO:0030434), atrial fibrillation (MONDO:0004981), cardiomyopathy (MONDO:0004994), hypertrophic cardiomyopathy (MONDO:0005045), ventricular tachycardia (MONDO:0005477), left ventricular noncompaction (MONDO:0018901), dilated cardiomyopathy (MONDO:0005021), Brugada syndrome (MONDO:0015263), long QT syndrome (MONDO:0002442), sinoatrial node disorder (MONDO:0000469), cardiac arrest (MONDO:0000745), arrhythmogenic right ventricular cardiomyopathy (MONDO:0016587), congestive heart failure (MONDO:0005009)

Orphanet (7): Brugada syndrome (Orphanet:130), Hereditary sick sinus syndrome (Orphanet:166282), Rare cardiomyopathy (Orphanet:167848), Rare hypertrophic cardiomyopathy (Orphanet:217569), Left ventricular noncompaction (Orphanet:54260), Dilated cardiomyopathy (Orphanet:217604), Inherited arrhythmogenic cardiomyopathy (Orphanet:247)

HPO phenotypes

41 total (30 of 41 shown, HPO-id order):

HPO	Term
HP:0000006	Autosomal dominant inheritance
HP:0000750	Delayed speech and language development
HP:0001256	Mild intellectual disability
HP:0001279	Syncope
HP:0001634	Mitral valve prolapse
HP:0001645	Sudden cardiac death
HP:0001649	Tachycardia
HP:0001659	Aortic regurgitation
HP:0001662	Bradycardia
HP:0001663	Ventricular fibrillation
HP:0001664	Torsade de pointes
HP:0001688	Sinus bradycardia
HP:0001695	Cardiac arrest
HP:0001712	Left ventricular hypertrophy
HP:0003577	Congenital onset
HP:0003581	Adult onset
HP:0003584	Late onset
HP:0003593	Infantile onset
HP:0003621	Juvenile onset
HP:0004308	Ventricular arrhythmia
HP:0004751	Paroxysmal ventricular tachycardia
HP:0004755	Supraventricular tachycardia
HP:0004756	Ventricular tachycardia
HP:0004757	Paroxysmal atrial fibrillation
HP:0005110	Atrial fibrillation
HP:0005184	Prolonged QTc interval
HP:0010872	T-wave inversion
HP:0011462	Young adult onset
HP:0011463	Childhood onset
HP:0011704	Sick sinus syndrome

GWAS associations

29 associations (top):

Study	Trait	p-value
GCST001499_10	Atrial fibrillation	3.000000e-17
GCST001969_14	Heart rate	4.000000e-20
GCST002928_15	Nickel levels	3.000000e-06
GCST003818_78	Resting heart rate	1.000000e-32
GCST004297_19	Atrial fibrillation	8.000000e-12
GCST004732_10	Heart rate variability traits (pvRSA/HF)	3.000000e-06
GCST004733_7	Heart rate variability traits (RMSSD)	1.000000e-10
GCST004734_16	Heart rate variability traits (SDNN)	5.000000e-11
GCST004734_17	Heart rate variability traits (SDNN)	3.000000e-11
GCST005789_27	Resting heart rate	2.000000e-09
GCST005956_11	Waist-to-hip ratio adjusted for BMI	1.000000e-08
GCST005962_52	Waist-to-hip ratio adjusted for BMI x sex x age interaction (4df test)	5.000000e-07
GCST006061_48	Atrial fibrillation	2.000000e-27
GCST006061_62	Atrial fibrillation	1.000000e-27
GCST006414_27	Atrial fibrillation	4.000000e-36
GCST006979_935	Heel bone mineral density	2.000000e-09
GCST010244_74	Triglyceride levels	2.000000e-09
GCST010320_6	PR interval	2.000000e-11
GCST010321_46	PR interval	2.000000e-12
GCST010703_184	Brain morphology (MOSTest)	5.000000e-11
GCST010796_446	Electrocardiogram morphology (amplitude at temporal datapoints)	5.000000e-10
GCST010796_447	Electrocardiogram morphology (amplitude at temporal datapoints)	4.000000e-08
GCST010796_448	Electrocardiogram morphology (amplitude at temporal datapoints)	5.000000e-08
GCST010796_449	Electrocardiogram morphology (amplitude at temporal datapoints)	1.000000e-08
GCST010796_450	Electrocardiogram morphology (amplitude at temporal datapoints)	1.000000e-09
GCST010796_501	Electrocardiogram morphology (amplitude at temporal datapoints)	4.000000e-09
GCST010796_502	Electrocardiogram morphology (amplitude at temporal datapoints)	2.000000e-08
GCST010796_503	Electrocardiogram morphology (amplitude at temporal datapoints)	1.000000e-08
GCST010796_504	Electrocardiogram morphology (amplitude at temporal datapoints)	1.000000e-08

EFO canonical traits (9, from GWAS)

EFO ID	Trait name
EFO:0008003	heart rate variability measurement
EFO:0007788	BMI-adjusted waist-hip ratio
EFO:0008007	age at assessment
EFO:0008343	sex interaction measurement
EFO:0009270	heel bone mineral density
EFO:0004530	triglyceride measurement
EFO:0004462	PR interval
EFO:0004346	neuroimaging measurement
EFO:0004327	electrocardiography

MeSH disease descriptors (12)

Descriptor	Name	Tree numbers
D019571	Arrhythmogenic Right Ventricular Dysplasia	C14.240.400.145; C14.280.238.028; C14.280.400.145; C16.131.240.400.145
D001281	Atrial Fibrillation	C14.280.067.198; C23.550.073.198
D053840	Brugada Syndrome	C14.280.067.322; C14.280.123.250; C16.320.100
D009202	Cardiomyopathies	C14.280.238
D002311	Cardiomyopathy, Dilated	C14.280.195.160; C14.280.238.070; C16.320.488.750
D002312	Cardiomyopathy, Hypertrophic	C14.280.238.100; C14.280.484.048.750.070.160
D006323	Heart Arrest	C14.280.383
D008133	Long QT Syndrome	C14.280.067.565; C14.280.123.625; C16.131.240.400.715; C23.550.073.547
D017180	Tachycardia, Ventricular	C14.280.067.845.940; C14.280.123.875.940; C23.550.073.845.940
C567732	Brugada Syndrome 8 (supp.)
C563907	Sick Sinus Syndrome 1, Autosomal Recessive (supp.)
C563513	Sick Sinus Syndrome 2, Autosomal Dominant (supp.)

Drugs & pharmacology

Drug and pharmacology data

Is drug target: yes

ChEMBL targets (1): CHEMBL1250417 (SINGLE PROTEIN)

Molecules with ChEMBL bioactivity

2 molecules (phase ≥1), by development phase (incl. off-target/promiscuous compounds). Patent mentions across the top 20 by phase: 3,622 (via chembl_molecule»patent_compound — counts attach to the compound, not the gene–compound relationship, so off-target/promiscuous molecules can dominate).

Molecule	Name	Phase	Patents
CHEMBL471737	IVABRADINE	4	2,989
CHEMBL69679	ZATEBRADINE	2	633

PharmGKB: 1 entry (VIP=true, CPIC=false)

GtoPdb / IUPHAR curated pharmacology

(IUPHAR/BPS Guide to Pharmacology — expert-curated)

Target class: vgic — Cyclic nucleotide-regulated channels (CNG)

Most potent curated ligand interactions (8 total), top 8:

Ligand	Action	Affinity	Parameter
cilobradine	Antagonist	6.0	pIC50
zatebradine	Antagonist	5.7	pIC50
ivabradine	Antagonist	5.7	pIC50
EC18	Channel blocker	5.4	pEC50
clonidine	Antagonist	5.01	pIC50
ZD7288	Antagonist	4.7	pIC50
MEL57A	Channel blocker	4.12	pEC50
Cs+	Antagonist	3.8	pIC50

ChEMBL bioactivities

23 potent at pChembl≥5 of 36 total, top 23 by pChembl (potency: 10 = 0.1 nM, 6 = 1 µM).

pChembl	Type	Value	Unit	Molecule
7.50	IC50	31.62	nM	CHEMBL2052019
6.80	IC50	158.5	nM	CHEMBL1823878
6.50	IC50	316.2	nM	CHEMBL1823874
6.50	IC50	316.2	nM	CHEMBL1823879
6.10	IC50	794.3	nM	CHEMBL1823875
6.10	IC50	794.3	nM	CHEMBL1823880
6.10	IC50	794.3	nM	CHEMBL1823881
5.90	IC50	1259	nM	CHEMBL1823677
5.80	IC50	1585	nM	CHEMBL1823876
5.60	IC50	2512	nM	CHEMBL1823667
5.50	IC50	3162	nM	CHEMBL1823674
5.40	EC50	3980	nM	CHEMBL4453882
5.40	IC50	3981	nM	CHEMBL1823882
5.40	IC50	3981	nM	CHEMBL1823887
5.37	EC50	4280	nM	IVABRADINE
5.30	IC50	5012	nM	CHEMBL1823666
5.30	IC50	5012	nM	CHEMBL1435630
5.30	IC50	5012	nM	CHEMBL1823886
5.30	IC50	5012	nM	CHEMBL1823888
5.20	IC50	6310	nM	CHEMBL1823885
5.15	EC50	7140	nM	CHEMBL1254085
5.14	EC50	7230	nM	CHEMBL1253993
5.07	EC50	8570	nM	ZATEBRADINE

PubChem BioAssay actives

23 with measured affinity, of 92 total; 23 most potent distinct compounds. Largely complementary to BindingDB; screening values are coarse (µM, 4 dp), so sub-nM hits tie at the floor.

Compound	Assay	Type	Value	Unit
4-N-ethyl-6-N,1,2-trimethyl-4-N-phenylpyrimidin-1-ium-4,6-diamine chloride	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	0.0316	uM
2-ethoxy-N-[[1-(4-ethylpiperazin-1-yl)cyclohexyl]methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	0.1585	uM
2-ethoxy-N-[[1-(4-propan-2-ylpiperazin-1-yl)cyclohexyl]methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	0.3162	uM
N-[[1-(4-cyclopropylpiperazin-1-yl)cyclohexyl]methyl]-2-ethoxybenzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	0.3162	uM
N-[[1-(4-cyclobutylpiperazin-1-yl)cyclohexyl]methyl]-2-ethoxybenzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	0.7943	uM
2-methoxy-N-[[1-(4-propan-2-ylpiperazin-1-yl)cyclohexyl]methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	0.7943	uM
N-[[1-(4-cyclopentylpiperazin-1-yl)cyclohexyl]methyl]-2-ethoxybenzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	0.7943	uM
2-ethoxy-N-[[1-(4-methylpiperazin-1-yl)cyclohexyl]methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	1.2589	uM
2-propan-2-yloxy-N-[[1-(4-propan-2-ylpiperazin-1-yl)cyclohexyl]methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	1.5849	uM
N-[[2-(4-methylpiperazin-1-yl)-1,3-dihydroinden-2-yl]methyl]-2-phenylmethoxybenzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	2.5119	uM
2-ethoxy-N-[[2-(4-propan-2-ylpiperazin-1-yl)-1,3-dihydroinden-2-yl]methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	3.1623	uM
3-[(1S,3R)-3-[2-(3,4-dimethoxyphenyl)ethyl-methylamino]cyclohexyl]-7,8-dimethoxy-2,5-dihydro-1H-3-benzazepin-4-one	1633603: Inhibition of human HCN4 expressed in HEK293 cells assessed as reduction in hyperpolarization activated current at holding potential of -80 mV by patch clamp assay	ec50	3.9800	uM
2-ethoxy-N-[(1-piperazin-1-ylcyclohexyl)methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	3.9811	uM
2-ethoxy-N-[[4-(4-propan-2-ylpiperazin-1-yl)oxan-4-yl]methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	3.9811	uM
Ivabradine	515585: Blockade of human HCN4 expressed in HEK293 cells at -120 f-current amplitude by patch-clamp electrophysiological assay	ec50	4.2800	uM
2-methoxy-N-[[1-(4-methylpiperazin-1-yl)cyclohexyl]methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	5.0119	uM
2-ethoxy-N-[[1-(4-methylpiperazin-1-yl)cyclopentyl]methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	5.0119	uM
2-ethoxy-N-[[2-(4-methylpiperazin-1-yl)-1,3-dihydroinden-2-yl]methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	5.0119	uM
2-methoxy-N-[[1-phenyl-4-(4-propan-2-ylpiperazin-1-yl)piperidin-4-yl]methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	5.0119	uM
2-methoxy-N-[[2-(4-methylpiperazin-1-yl)-3,4-dihydro-1H-naphthalen-2-yl]methyl]benzamide	617260: Inhibition of human HCN4 heterologously expressed in HEK-293 cells after 30 mins by VIPR assay	ic50	6.3096	uM
3-[(Z)-4-[2-(3,4-dimethoxyphenyl)ethyl-methylamino]but-2-enyl]-7,8-dimethoxy-1H-3-benzazepin-2-one	515585: Blockade of human HCN4 expressed in HEK293 cells at -120 f-current amplitude by patch-clamp electrophysiological assay	ec50	7.1400	uM
3-[(E)-4-[2-(3,4-dimethoxyphenyl)ethyl-methylamino]but-2-enyl]-7,8-dimethoxy-1H-3-benzazepin-2-one	515585: Blockade of human HCN4 expressed in HEK293 cells at -120 f-current amplitude by patch-clamp electrophysiological assay	ec50	7.2300	uM
3-[3-[2-(3,4-dimethoxyphenyl)ethyl-methylamino]propyl]-7,8-dimethoxy-2,5-dihydro-1H-3-benzazepin-4-one	515585: Blockade of human HCN4 expressed in HEK293 cells at -120 f-current amplitude by patch-clamp electrophysiological assay	ec50	8.5700	uM

CTD chemical–gene interactions

32 total (human), top 30 by PubMed support.

Chemical	Actions (top 5)	PubMed papers
Aflatoxin B1	decreases expression, decreases methylation	3
entinostat	increases expression, affects cotreatment	2
Benzo(a)pyrene	increases methylation, affects methylation	2
propionaldehyde	increases expression	1
sodium arsenite	decreases expression	1
butyraldehyde	increases expression	1
benzo(e)pyrene	affects methylation	1
ferrous chloride	decreases expression	1
S-(1,2-dichlorovinyl)cysteine	decreases reaction, increases expression	1
pentanal	increases expression	1
1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene	increases expression, affects cotreatment	1
4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide	affects cotreatment, increases expression	1
nutlin 3	increases expression, affects cotreatment	1
abrine	increases expression	1
dorsomorphin	affects cotreatment, increases expression	1
Sunitinib	decreases expression	1
Acetaminophen	increases expression	1
Aconitine	affects binding, increases reaction, increases expression	1
Aldehydes	increases expression	1
Cadmium	decreases expression	1
Dactinomycin	affects cotreatment, increases expression	1
Diazinon	decreases methylation	1
Doxorubicin	decreases expression	1
Flecainide	decreases activity	1
Formaldehyde	decreases expression	1
Lipopolysaccharides	increases expression, decreases reaction	1
Methapyrilene	affects methylation	1
Phenylbutyrates	affects cotreatment, increases expression	1
Tobacco Smoke Pollution	decreases expression	1
Tretinoin	affects cotreatment, increases expression	1

ChEMBL screening assays

30 unique, capped per target: 20 binding, 5 admet, 4 functional, 1 toxicity

Representative assays (with source publication via chembl_document):

Assay ID	Type	Description	Source paper
CHEMBL1250985	Binding	Blockade of human HCN4 expressed in HEK293 cells at 5 uM at -120 f-current amplitude by patch-clamp electrophysiological assay relative to control	Design, synthesis, and preliminary biological evaluation of new isoform-selective f-current blockers. — J Med Chem
CHEMBL4039287	ADMET	Inhibition of human HCN4 expressed in CHO cells by automated patch clamp assay	Discovery of N-(5-Fluoropyridin-2-yl)-6-methyl-4-(pyrimidin-5-yloxy)picolinamide (VU0424238): A Novel Negative Allosteric Modulator of Metabotropic Glutamate Receptor Subtype 5 Selected for Clinical Evaluation. — J Med Chem
CHEMBL5258218	Toxicity	Inhibition of HCN4 (unknown origin) at 10 uM	Discovery of VU2957 (Valiglurax): An mGlu4 Positive Allosteric Modulator Evaluated as a Preclinical Candidate for the Treatment of Parkinson’s Disease. — ACS Med Chem Lett

Cellosaurus cell lines

4 cell lines: 2 induced pluripotent stem cell, 1 cancer cell line, 1 spontaneously immortalized cell line

First 10 cell lines (id-ordered, not curated):

Cellosaurus	Name	Category	Sex
CVCL_C1SA	SCVIi063-A	Induced pluripotent stem cell	Female
CVCL_C1SB	SCVIi064-A	Induced pluripotent stem cell	Male
CVCL_D8M9	Ubigene HCT 116 HCN4 KO	Cancer cell line	Male
CVCL_RQ82	PrecisION hHCN4-CHO	Spontaneously immortalized cell line	Female

Clinical trials (associated diseases)

302 trials via MONDO — disease-level, not drug-specific.

Trial	Phase	Status	Title
NCT00032591	PHASE4	COMPLETED	The Home INR Study
NCT00127712	PHASE4	COMPLETED	Prevention of Atrial Fibrillation Following Noncardiac Thoracic Surgery
NCT00157781	PHASE4	COMPLETED	LEAF - Low Energy In Atrial Fibrillation
NCT00170313	PHASE4	TERMINATED	CORE: Study to Evaluate the Conducted AF-Response-Algorithm in Patients Suffering From Heart Failure and Atrial Fibrillation
NCT00189319	PHASE4	COMPLETED	To Evaluate the Impact of Oral Flecainide on Quality of Life in Patients With Paroxysmal Atrial Fibrillation
NCT00196144	PHASE4	COMPLETED	FFS - Far Field Sensing Test Study in Cardiac Dual Chamber Pacemakers
NCT00196157	PHASE4	UNKNOWN	Line Versus Spot Ablation in Persistent Atrial Fibrillation
NCT00196183	PHASE4	COMPLETED	Trigger- vs. Substrate-Ablation for Paroxysmal Atrial Fibrillation
NCT00196209	PHASE4	UNKNOWN	Cardioversion vs. Catheter Ablation for Persistent Atrial Fibrillation
NCT00227344	PHASE4	TERMINATED	CACAF2 Study: Catheter Ablation for Cure of Atrial Fibrillation
NCT00232219	PHASE4	COMPLETED	Use of Fish Oils to Reduce Recurrence of Atrial Fibrillation Following DC Cardioversion
NCT00232232	PHASE4	COMPLETED	Use of Fish Oils to Prevent Atrial Mechanical Stunning and Atrial Remodeling Due to Atrial Arrhythmia
NCT00232245	PHASE4	COMPLETED	Use of Fish Oils to Reduce the Frequency and Duration of Episodes of Atrial Fibrillation in Patients With Paroxysmal Atrial Fibrillation.
NCT00239226	PHASE4	COMPLETED	Electrophysiologically Guided PAcing Site Selection Study
NCT00247780	PHASE4	COMPLETED	Cavotricuspid Isthmusblock and Circumferential Pulmonary Vein Isolation in Patients With Atrial Fibrillation
NCT00256152	PHASE4	COMPLETED	Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the Atrial Fibrillation Reduction Atrial Pacing Trial
NCT00262119	PHASE4	COMPLETED	MINERVA: MINimizE Right Ventricular Pacing to Prevent Atrial Fibrillation and Heart Failure
NCT00287209	PHASE4	COMPLETED	Reduction of Atrial Fibrillation Study in Patients Undergoing Coronary Artery Bypass Grafting. (RASCABG 1 Study)
NCT00289042	PHASE4	COMPLETED	Assessment of Cardioversion Using Transesophageal Echocardiography II (ACUTE II)
NCT00313443	PHASE4	COMPLETED	Concentrations of Amiodarone in Fat Tissue During Chronic Treatment
NCT00340314	PHASE4	COMPLETED	A Trial of Circumferential Pulmonary Vein Ablation (CPVA) Versus Antiarrhythmic Drug Therapy in for Paroxysmal Atrial Fibrillation (AF)
NCT00343499	PHASE4	TERMINATED	The Use of DIOVAN to Reduce Post-Cardioversion Recurrence of Atrial Fibrillation Trial (the DRAFT Trial)
NCT00408473	PHASE4	TERMINATED	Comparative Study of Flecainide CR and Placebo in the Early Treatment of Atrial Fibrillation.
NCT00420017	PHASE4	COMPLETED	Prevention of Atrial Fibrillation Following Esophagectomy
NCT00438113	PHASE4	COMPLETED	Atrial Substrate Modification With Aggressive Blood Pressure Lowering to Prevent AF
NCT00446966	PHASE4	COMPLETED	Fish Oil for Reduction of Atrial Fibrillation After Cardiac Surgery
NCT00449410	PHASE4	COMPLETED	Silent Cerebrovascular Lesion and Cognitive Decline Prevention by Cholesterol Lowering in Elderly AF Patients
NCT00466973	PHASE4	WITHDRAWN	Atrial Fibrillation Ablation Device Comparison Study
NCT00511173	PHASE4	COMPLETED	Comparison of Warfarin Dosing Using Decision Model Versus Pharmacogenetic Algorithm
NCT00512915	PHASE4	COMPLETED	Avoid FFS - Use of the Atrial Pacemaker Lead 1699 With Very Short Tip Ring Spacing to Avoid Far Field Sensing
NCT00552084	PHASE4	COMPLETED	Evaluating the Effectiveness of Fish Oil Supplements at Reducing the Recurrence of Atrial Fibrillation
NCT00559988	PHASE4	TERMINATED	Combined Use of BIOTRONIK Home Monitoring and Predefined Anticoagulation to Reduce Stroke Risk
NCT00579098	PHASE4	COMPLETED	The Use of Statins Following a Left Atrial Catheter Ablation Procedure to Prevent Atrial Fibrillation
NCT00586287	PHASE4	COMPLETED	Study to Find Out the Appropriate Initial Dose of the Anticoagulant Drug Phenprocoumon
NCT00597077	PHASE4	COMPLETED	Atrial Fibrillation and Congestive Heart Failure Trial
NCT00603317	PHASE4	COMPLETED	Pharmacodynamic Drug Interaction Between Warfarin and Amoxicillin-clavulanic Acid
NCT00605748	PHASE4	UNKNOWN	Pulmonary Vein (PV) -Isolation: Arrhythmogenic Vein(s) Versus All Veins
NCT00643188	PHASE4	COMPLETED	Catheter Ablation vs. Standard Conventional Treatment in Patients With LV Dysfunction and AF
NCT00678340	PHASE4	COMPLETED	Randomized Trial of Two Ablation Catheters in Paroxysmal Atrial Fibrillation
NCT00680927	PHASE4	COMPLETED	Reveal® XT Performance Trial (XPECT)