KRTAP9-9

Summary

KRTAP9-9 (keratin associated protein 9-9, HGNC:16773) is a protein-coding gene on chromosome 17q21.2, encoding Keratin-associated protein 9-9 (Q9BYP9). In the hair cortex, hair keratin intermediate filaments are embedded in an interfilamentous matrix, consisting of hair keratin-associated proteins (KRTAP), which are essential for the formation of a rigid and resistant hair shaft through their extensive disulfide bond cross-link….

This protein is a member of the keratin-associated protein (KAP) family. The KAP proteins form a matrix of keratin intermediate filaments which contribute to the structure of hair fibers. KAP family members appear to have unique, family-specific amino- and carboxyl-terminal regions and are subdivided into three multi-gene families according to amino acid composition: the high sulfur, the ultrahigh sulfur, and the high tyrosine/glycine KAPs. This protein is a member of the ultrahigh sulfur KAP family and the gene is localized to a cluster of KAPs at 17q12-q21. Alternative haplotypes of this gene are represented in the GRCh38 reference genome assembly.

Source: NCBI Gene 81870 — RefSeq curated summary.

At a glance

• Clinical variants (ClinVar): 27 total
• MANE Select transcript: NM_030975

Identifiers

Gene identifiers

Field	Value
HGNC ID	HGNC:16773
Approved symbol	KRTAP9-9
Name	keratin associated protein 9-9
Location	17q21.2
Locus type	gene with protein product
Status	Approved
Aliases	KAP9.9, KAP9.5
Ensembl gene	ENSG00000198083
Ensembl biotype	protein_coding
Entrez	81870

Gene structure

Transcript identifiers

Ensembl transcripts: 1 — 1 protein_coding

ENST00000394008

RefSeq mRNA: 1 — MANE Select: NM_030975 NM_030975

CCDS: CCDS54127

Canonical transcript exons

ENST00000394008 — 1 exons

Exon	Start	End
ENSE00001517201	41255384	41256364

Expression profiles

Bgee: expression breadth broad, 19 present calls, max score 37.67.

Top tissues by expression

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

Tissue	Anatomy ID	Expression score	Quality
skin of abdomen	UBERON:0001416	37.67	gold quality
colonic epithelium	UBERON:0000397	37.20	gold quality
ventricular zone	UBERON:0003053	36.48	gold quality
cortical plate	UBERON:0005343	36.47	gold quality
bone marrow cell	CL:0002092	36.16	gold quality
zone of skin	UBERON:0000014	35.62	gold quality
ganglionic eminence	UBERON:0004023	35.49	gold quality
skin of leg	UBERON:0001511	34.29	gold quality
right lung	UBERON:0002167	33.94	gold quality
skeletal muscle tissue	UBERON:0001134	33.38	gold quality
hindlimb stylopod muscle	UBERON:0004252	32.15	gold quality
bone marrow	UBERON:0002371	31.74	gold quality
muscle tissue	UBERON:0002385	31.06	gold quality
sural nerve	UBERON:0015488	30.93	gold quality
liver	UBERON:0002107	29.93	gold quality
stromal cell of endometrium	CL:0002255	29.87	gold quality
prefrontal cortex	UBERON:0000451	29.04	gold quality
duodenum	UBERON:0002114	28.14	gold quality
blood	UBERON:0000178	27.83	silver quality
right coronary artery	UBERON:0001625	27.63	gold quality
lymph node	UBERON:0000029	27.57	gold quality
right lobe of liver	UBERON:0001114	27.25	gold quality
tonsil	UBERON:0002372	27.05	gold quality
muscle of leg	UBERON:0001383	26.91	gold quality
islet of Langerhans	UBERON:0000006	26.55	gold quality
vermiform appendix	UBERON:0001154	26.42	gold quality
leukocyte	CL:0000738	26.19	gold quality
gastrocnemius	UBERON:0001388	26.14	gold quality
monocyte	CL:0000576	26.06	gold quality
gall bladder	UBERON:0002110	25.98	gold quality

Single-cell (SCXA)

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

Experiment	Marker?	Max mean expression
E-ANND-3	no	0.00

Regulation

Is transcription factor: no

miRNA regulators (miRDB)

46 targeting KRTAP9-9, 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-513B-5P	99.99	69.96	2150
HSA-MIR-223-3P	99.99	70.14	1140
HSA-MIR-3658	99.96	73.87	4379
HSA-MIR-570-3P	99.96	72.41	4910
HSA-MIR-381-3P	99.93	71.87	2854
HSA-MIR-300	99.92	71.76	2856
HSA-MIR-548AG	99.77	69.25	1492
HSA-MIR-548AI	99.69	69.24	1494
HSA-MIR-548BA	99.69	69.14	1514
HSA-MIR-570-5P	99.69	69.24	1494
HSA-MIR-580-3P	99.67	69.23	1841
HSA-MIR-7156-5P	99.64	68.81	1369
HSA-MIR-891B	99.59	69.81	1083
HSA-MIR-3123	99.47	67.15	2693
HSA-MIR-4273	99.45	67.93	1206
HSA-MIR-4311	99.31	70.47	3041
HSA-MIR-3678-3P	99.31	67.10	1432
HSA-MIR-888-5P	99.30	70.15	1855
HSA-MIR-4291	99.20	68.88	2969
HSA-MIR-4426	99.17	66.74	1949
HSA-MIR-922	99.02	67.23	1838
HSA-MIR-4699-5P	98.99	67.50	1210
HSA-MIR-4709-3P	98.88	68.04	1594
HSA-MIR-6760-5P	98.87	66.73	1515
HSA-MIR-4477A	98.83	69.75	2952
HSA-MIR-3611	98.76	68.76	1290
HSA-MIR-214-3P	98.71	68.12	2128
HSA-MIR-761	98.71	68.07	2051
HSA-MIR-3928-5P	98.50	67.48	980
HSA-MIR-6806-3P	98.50	67.31	980

Cross-species orthologs

0 orthologs

Paralogs (47): KRTAP4-4 (ENSG00000171396), KRTAP9-7 (ENSG00000180386), KRTAP5-5 (ENSG00000185940), KRTAP12-1 (ENSG00000187175), KRTAP9-8 (ENSG00000187272), KRTAP10-8 (ENSG00000187766), KRTAP10-6 (ENSG00000188155), KRTAP1-1 (ENSG00000188581), KRTAP10-12 (ENSG00000189169), KRTAP4-3 (ENSG00000196156), KRTAP4-6 (ENSG00000198090), KRTAP4-5 (ENSG00000198271), KRTAP4-1 (ENSG00000198443), KRTAP9-3 (ENSG00000204873), KRTAP4-8 (ENSG00000204880), KRTAP1-4 (ENSG00000204887), KRTAP12-3 (ENSG00000205439), KRTAP10-2 (ENSG00000205445), KRTAP5-6 (ENSG00000205864), KRTAP5-2 (ENSG00000205867), KRTAP16-1 (ENSG00000212657), KRTAP9-6 (ENSG00000212659), KRTAP4-11 (ENSG00000212721), KRTAP4-9 (ENSG00000212722), KRTAP2-3 (ENSG00000212724), KRTAP2-1 (ENSG00000212725), KRTAP10-3 (ENSG00000212935), KRTAP4-12 (ENSG00000213416), KRTAP2-4 (ENSG00000213417), KRTAP2-2 (ENSG00000214518), KRTAP10-4 (ENSG00000215454), KRTAP10-1 (ENSG00000215455), KRTAP10-9 (ENSG00000221837), KRTAP1-5 (ENSG00000221852), KRTAP10-10 (ENSG00000221859), KRTAP12-2 (ENSG00000221864), KRTAP1-3 (ENSG00000221880), KRTAP9-2 (ENSG00000239886), KRTAP9-1 (ENSG00000240542), KRTAP4-7 (ENSG00000240871)

Protein

Protein identifiers

Keratin-associated protein 9-9 — Q9BYP9 (reviewed: Q9BYP9)

Alternative names: Keratin-associated protein 9-5, Keratin-associated protein 9.5, Keratin-associated protein 9.9, Ultrahigh sulfur keratin-associated protein 9.9

All UniProt accessions (1): Q9BYP9

UniProt curated annotations — full annotation on UniProt →

Function. In the hair cortex, hair keratin intermediate filaments are embedded in an interfilamentous matrix, consisting of hair keratin-associated proteins (KRTAP), which are essential for the formation of a rigid and resistant hair shaft through their extensive disulfide bond cross-linking with abundant cysteine residues of hair keratins. The matrix proteins include the high-sulfur and high-glycine-tyrosine keratins.

Subunit / interactions. Interacts with hair keratins.

Similarity. Belongs to the KRTAP type 9 family.

Isoforms (3)

UniProt ID	Names	Canonical?
Q9BYP9-1	1	yes
Q9BYP9-2	2
Q9BYP9-3	3

RefSeq proteins (1): NP_112237* (*=MANE)

Domains & families (InterPro)

ID	Name	Type
IPR002494	KAP	Family

Pfam: PF13885

UniProt features (20 total): repeat 14, splice variant 2, sequence variant 2, chain 1, region of interest 1

Structure

Experimental structures (PDB)

0 structures.

Predicted structure (AlphaFold)

Model	pLDDT	Fraction very-high
AF-Q9BYP9-F1	39.63	0.00

Function

Pathways and Gene Ontology

Reactome pathways

2 pathways

ID	Pathway
R-HSA-6805567	Keratinization
R-HSA-1266738	Developmental Biology

MSigDB gene sets: 32 (showing top): GU_PDEF_TARGETS_DN, MARTINEZ_RB1_TARGETS_DN, GOCC_INTERMEDIATE_FILAMENT_CYTOSKELETON, GOCC_KERATIN_FILAMENT, GOCC_SUPRAMOLECULAR_COMPLEX, GOCC_POLYMERIC_CYTOSKELETAL_FIBER, REACTOME_KERATINIZATION, GOCC_SUPRAMOLECULAR_POLYMER, MIR3658, MIR4477A, MIR513B_5P, MIR548BA, MIR548AI_MIR570_5P, MIR548AG, MIR3611

GO Biological Process (0):

GO Molecular Function (0):

GO Cellular Component (3): cytosol (GO:0005829), keratin filament (GO:0045095), intermediate filament (GO:0005882)

Reactome top-level categories

Rollup of top-1 pathways:

Category	Pathways
Developmental Biology	1

GO top-level categories

Rollup of top GO terms by namespace:

Category	Terms
cytoplasm	1
cellular anatomical structure	1
intermediate filament	1
intermediate filament cytoskeleton	1
polymeric cytoskeletal fiber	1

Protein interactions and networks

STRING

0 interactions, top by confidence (×1000):

IntAct

0 interactions, top by confidence:

BioGRID (1): KRTAP9-9 (Affinity Capture-MS)

ESM2 similar proteins: A5A6P5, A6QP35, A8MTY7, A8MVA2, A8MXZ3, O75690, P02438, P02441, P02442, P02443, P08131, P0C7H8, P26371, P59990, P59991, P60014, P60331, P60368, P60369, P60370, P60371, P60372, P60409, P60410, P60411, P60412, P60413, Q05B44, Q07627, Q3V2C1, Q6L8G4, Q6L8G8, Q6L8G9, Q6L8H2, Q701N4, Q8IUG1, Q9BQ66, Q9BYP9, Q9BYQ0, Q9BYQ2

Diamond homologs: A5A6P5, Q9BYP9, Q9BYQ0, Q9BYQ2, Q9BYQ3, Q9BYQ4, A8MTY7, A8MVA2

SIGNOR signaling

0 interactions.

Disease & clinical

Clinical variants and AI predictions

ClinVar

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

Classification	Count (floor)
Pathogenic	0
Likely pathogenic	0
Uncertain significance	25
Likely benign	2
Benign	0

Top pathogenic / likely-pathogenic (0)

SpliceAI

192 predictions. Top by Δscore:

Variant	Effect	Δscore
17:41256185:T:G	donor_gain	0.7400
17:41256194:T:G	donor_gain	0.7200
17:41256194:T:TG	donor_gain	0.6900
17:41256106:T:G	acceptor_gain	0.6000
17:41255669:GCT:G	donor_gain	0.5900
17:41256093:A:AG	acceptor_gain	0.5600
17:41256210:GAT:G	donor_gain	0.5600
17:41255823:G:GT	donor_gain	0.5500
17:41255838:G:GT	donor_gain	0.5500
17:41256094:C:G	acceptor_gain	0.5500
17:41255757:T:TA	acceptor_gain	0.5300
17:41255864:T:A	donor_gain	0.5300
17:41256054:G:GT	donor_gain	0.5300
17:41256055:G:T	donor_gain	0.5300
17:41256059:G:T	donor_gain	0.5200
17:41256212:T:G	donor_gain	0.5100
17:41256099:T:TA	acceptor_gain	0.5000
17:41256093:ACCTT:A	acceptor_gain	0.4900
17:41256228:C:G	donor_gain	0.4900
17:41256102:A:G	donor_gain	0.4800
17:41256228:C:CG	donor_gain	0.4800
17:41255559:G:GT	donor_gain	0.4700
17:41255642:G:GG	donor_gain	0.4700
17:41255962:GAC:G	donor_gain	0.4700
17:41256199:T:G	donor_gain	0.4700
17:41256185:T:TG	donor_gain	0.4600
17:41256193:C:G	donor_gain	0.4600
17:41255442:G:GT	donor_gain	0.4500
17:41256163:TC:T	donor_gain	0.4500
17:41256097:T:A	acceptor_gain	0.4400

AlphaMissense

1114 scored. Top likely-pathogenic:

dbSNP variants (sampled 300 via entrez): RS1000590823 (17:41253647 A>C), RS1000692699 (17:41254123 A>C), RS1000809764 (17:41254341 C>T), RS1001618346 (17:41256078 TTC>T), RS1002364956 (17:41255221 A>C,G), RS1002820273 (17:41256800 G>A), RS1004205617 (17:41256856 AT>A,ATT), RS1004903536 (17:41256384 A>G), RS1005258159 (17:41256738 C>T), RS1007390438 (17:41254478 A>T), RS1007408776 (17:41253450 T>A), RS1007465826 (17:41255606 C>A,T), RS1007825470 (17:41254779 C>A,T), RS1008484966 (17:41256416 A>G), RS1009780521 (17:41254523 G>A)

Disease associations

OMIM: gene `` | 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

6 total (human), top 6 by PubMed support.

Chemical	Actions (top 5)	PubMed papers
Grape Seed Proanthocyanidins	affects cotreatment, decreases expression	1
Benzo(a)pyrene	decreases expression	1
Catechin	affects cotreatment, decreases expression	1
Endosulfan	decreases expression	1
Zinc	decreases expression	1
Aflatoxin B1	decreases methylation	1

Clinical trials (associated diseases)

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