MUC3B

Summary

MUC3B (mucin 3B, cell surface associated, HGNC:13384) is a protein-coding gene on chromosome 7q22 not on reference assembly, encoding Mucin-3B (Q9H195). Major glycoprotein component of a variety of mucus gels.

Predicted to be located in Golgi lumen and plasma membrane.

Source: NCBI Gene 57876 — RefSeq curated summary.

Identifiers

Gene identifiers

Field	Value
HGNC ID	HGNC:13384
Approved symbol	MUC3B
Name	mucin 3B, cell surface associated
Location	7q22 not on reference assembly
Locus type	gene with protein product
Status	Approved
OMIM	605633
Entrez	57876

Gene structure

Transcript identifiers

Ensembl transcripts: 0

RefSeq mRNA: 0 — MANE Select: None

Canonical transcript exons

None — 0 exons

Expression profiles

Top tissues by expression

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

Regulation

Is transcription factor: no

Literature-anchored findings (GeneRIF, showing 3)

• has highly conserved amino and carboxyl termini, suggesting a recent duplication of the entire ancestral gene (PMID:12958310)
• up-regulated MUC expression by synovial tissue cells and suggest a novel role of MUC3 and MUC5AC in the pathogenesis of arthritis (PMID:18163520)
• Discovery of a MUC3B gene reconstructs the membrane mucin gene cluster on human chromosome 7. (PMID:36256656)

Cross-species orthologs

0 orthologs

Protein

Protein identifiers

Mucin-3B — Q9H195 (reviewed: Q9H195)

Alternative names: Intestinal mucin-3B

All UniProt accessions (0):

UniProt curated annotations — full annotation on UniProt →

Function. Major glycoprotein component of a variety of mucus gels. Thought to provide a protective, lubricating barrier against particles and infectious agents at mucosal surfaces.

Subcellular location. Membrane.

Tissue specificity. Fetal and adult small intestine and fetal and adult colon.

Post-translational modifications. Highly O-glycosylated and probably also N-glycosylated.

RefSeq proteins (0): (*=MANE)

Domains & families (InterPro)

ID	Name	Type
IPR000082	SEA_dom	Domain
IPR000742	EGF	Domain
IPR002049	LE_dom	Domain
IPR036364	SEA_dom_sf	Homologous_superfamily
IPR052504	Mucin_signaling_protection	Family

UniProt features (230 total): compositionally biased region 110, region of interest 106, sequence conflict 4, disulfide bond 2, sequence variant 2, domain 2, signal peptide 1, chain 1, transmembrane region 1, site 1

Structure

Experimental structures (PDB)

0 structures.

Predicted structure (AlphaFold)

No AlphaFold model available for Q9H195 — AlphaFold DB does not currently provide models for proteins above ~3000 aa.

Functional residue map

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

Catalytic / active sites (1): 13234–13235 (cleavage; by autolysis)

Disulfide bonds (2): 13134–13140, 13153–13162

Function

Pathways and Gene Ontology

Reactome pathways

6 pathways

ID	Pathway
R-HSA-5083625	Defective GALNT3 causes HFTC
R-HSA-5083632	Defective C1GALT1C1 causes TNPS
R-HSA-5083636	Defective GALNT12 causes CRCS1
R-HSA-5621480	Dectin-2 family
R-HSA-913709	O-linked glycosylation of mucins
R-HSA-977068	Termination of O-glycan biosynthesis

MSigDB gene sets: 0 (showing top):

GO Biological Process (0):

GO Molecular Function (0):

GO Cellular Component (2): Golgi lumen (GO:0005796), plasma membrane (GO:0005886)

Reactome top-level categories

Rollup of top-4 pathways:

Category	Pathways
Diseases associated with O-glycosylation of proteins	3
C-type lectin receptors (CLRs)	1
O-linked glycosylation	1
O-linked glycosylation of mucins	1

GO top-level categories

Rollup of top GO terms by namespace:

Category	Terms
Golgi apparatus	1
intracellular organelle lumen	1
membrane	1
cell periphery	1

Protein interactions and networks

STRING

0 interactions, top by confidence (×1000):

IntAct

108 interactions, top by confidence:

A	B	Type	Score
MUC3B	PDZD2	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	SNX27	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	SYNJ2BP	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	MAST2	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	PTPN3	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	PATJ	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	TAX1BP3	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	WHRN	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	DLG3	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	PICK1	psi-mi:“MI:0407”(direct interaction)	0.440
DLG4	MUC3B	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	DLG1	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	MAST1	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	ARHGEF12	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	SNTG1	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	TAMALIN	psi-mi:“MI:0407”(direct interaction)	0.440
GOPC	MUC3B	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	SNTG2	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	IL16	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	PDZK1	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	MAGI2	psi-mi:“MI:0407”(direct interaction)	0.440
APBA3	MUC3B	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	TIAM2	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	PDZD7	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	NHERF4	psi-mi:“MI:0407”(direct interaction)	0.440
CASK	MUC3B	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	MPP2	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	PTPN13	psi-mi:“MI:0407”(direct interaction)	0.440
MUC3B	DLG4	psi-mi:“MI:0407”(direct interaction)	0.440

ESM2 similar proteins: A0A0U1RQI7, A0A494C071, A6QL64, A6ZXT5, A7XUY5, E2RYF6, E2RYF7, O60732, O88799, P06916, P12021, P18583, P41809, P43537, P47179, P53353, Q00130, Q02496, Q02505, Q04893, Q05049, Q12459, Q14242, Q32KG4, Q4ZJY7, Q4ZJZ0, Q54QZ8, Q5H9R4, Q5H9T9, Q5JPF3, Q5SSG8, Q5XHX6, Q60528, Q63661, Q685J3, Q6P902, Q86VQ3, Q8JZM8, Q8N307, Q8NET4

Diamond homologs: Q02505, Q9H195

SIGNOR signaling

0 interactions.

Enriched among interaction partners

Reactome pathways and GO biological processes over-represented among this gene’s 74 IntAct physical interaction partners (hypergeometric vs the genome-wide background, BH-FDR, gene-set size 15–500, ranked by fold). A functional readout of the neighbourhood — distinct from this gene’s own memberships above, and biased toward well-studied / hub proteins, so read it as themes rather than proof.

Reactome pathways:

Pathway	Partners	Fold	FDR
Assembly and cell surface presentation of NMDA receptors	8	43.2×	2e-09
Neurexins and neuroligins	8	33.5×	7e-09
Protein-protein interactions at synapses	5	28.2×	5e-05

GO biological processes:

GO term	Partners	Fold	FDR
establishment or maintenance of epithelial cell apical/basal polarity	10	80.7×	1e-14
receptor clustering	6	52.0×	2e-07
regulation of postsynaptic membrane neurotransmitter receptor levels	6	41.3×	7e-07
cell-cell adhesion	9	12.7×	3e-06
protein-containing complex assembly	8	12.7×	2e-05
protein localization to plasma membrane	5	7.5×	9e-03
chemical synaptic transmission	6	6.4×	7e-03

Disease & clinical

Clinical variants and AI predictions

ClinVar

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

Classification	Count (floor)
Pathogenic	0
Likely pathogenic	0
Uncertain significance	0
Likely benign	0
Benign	0

Top pathogenic / likely-pathogenic (0)

SpliceAI

0 predictions. Top by Δscore:

AlphaMissense

0 scored. Top likely-pathogenic:

Disease associations

OMIM: gene MIM:605633 | disease phenotypes:

GenCC curated gene-disease

Mondo (0):

Orphanet (0):

HPO phenotypes

0 total (0 of 0 shown, HPO-id order):

GWAS associations

0 associations (top):

Drugs & pharmacology

Drug and pharmacology data

Is drug target: no

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

CTD chemical–gene interactions

2 total (human), top 2 by PubMed support.

Chemical	Actions (top 5)	PubMed papers
Arsenic Trioxide	decreases response to substance	1
Valproic Acid	increases expression	1

Clinical trials (associated diseases)

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