KRTAP9-8

Summary

KRTAP9-8 (keratin associated protein 9-8, HGNC:17231) is a protein-coding gene on chromosome 17q21.2, encoding Keratin-associated protein 9-8 (Q9BYQ0). 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.

Source: NCBI Gene 83901 — RefSeq curated summary.

At a glance

• Clinical variants (ClinVar): 34 total
• MANE Select transcript: NM_031963

Identifiers

Gene identifiers

Field	Value
HGNC ID	HGNC:17231
Approved symbol	KRTAP9-8
Name	keratin associated protein 9-8
Location	17q21.2
Locus type	gene with protein product
Status	Approved
Aliases	KAP9.8
Ensembl gene	ENSG00000187272
Ensembl biotype	protein_coding
Entrez	83901

Gene structure

Transcript identifiers

Ensembl transcripts: 1 — 1 protein_coding

ENST00000254072

RefSeq mRNA: 1 — MANE Select: NM_031963 NM_031963

CCDS: CCDS42334

Canonical transcript exons

ENST00000254072 — 1 exons

Exon	Start	End
ENSE00001272334	41237999	41239004

Expression profiles

Bgee: expression breadth broad, 26 present calls, max score 41.11.

FANTOM5 (CAGE): breadth tissue_specific, TPM avg 0.0101 / max 15.7807, expressed in 2 samples.

FANTOM5 promoters (1 alternative TSS)

Promoter ID	TPM avg	Samples expressed
160819	0.0101	2

Top tissues by expression

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

Tissue	Anatomy ID	Expression score	Quality
skin of abdomen	UBERON:0001416	41.11	gold quality
zone of skin	UBERON:0000014	39.06	gold quality
skin of leg	UBERON:0001511	37.84	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
ganglionic eminence	UBERON:0004023	35.49	gold quality
skeletal muscle tissue	UBERON:0001134	33.38	gold quality
right lung	UBERON:0002167	32.60	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
stromal cell of endometrium	CL:0002255	29.87	gold quality
prefrontal cortex	UBERON:0000451	29.04	gold quality
blood	UBERON:0000178	28.98	gold quality
muscle of leg	UBERON:0001383	28.52	gold quality
duodenum	UBERON:0002114	28.14	gold quality
gastrocnemius	UBERON:0001388	28.11	gold quality
primary visual cortex	UBERON:0002436	27.76	gold quality
lymph node	UBERON:0000029	27.57	gold quality
leukocyte	CL:0000738	27.22	gold quality
monocyte	CL:0000576	27.18	gold quality
urinary bladder	UBERON:0001255	26.96	gold quality
vermiform appendix	UBERON:0001154	26.42	gold quality
kidney	UBERON:0002113	26.12	silver quality
gall bladder	UBERON:0002110	25.98	gold quality
adult mammalian kidney	UBERON:0000082	25.90	silver quality
olfactory segment of nasal mucosa	UBERON:0005386	25.89	gold quality

Single-cell (SCXA)

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

Experiment	Marker?	Max mean expression
E-ANND-3	no	0.16

Regulation

Is transcription factor: no

miRNA regulators (miRDB)

42 targeting KRTAP9-8, 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-3613-3P	100.00	76.36	7965
HSA-MIR-3605-5P	99.96	67.12	932
HSA-MIR-570-3P	99.96	72.41	4910
HSA-MIR-651-3P	99.94	73.48	5177
HSA-MIR-381-3P	99.93	71.87	2854
HSA-MIR-300	99.92	71.76	2856
HSA-MIR-16-5P	99.90	72.80	2780
HSA-MIR-494-3P	99.70	71.45	2795
HSA-MIR-518A-5P	99.70	69.01	2209
HSA-MIR-527	99.70	69.01	2209
HSA-MIR-7154-5P	99.69	70.52	1900
HSA-MIR-580-3P	99.67	69.23	1841
HSA-MIR-6832-5P	99.58	64.82	1132
HSA-MIR-12123	99.52	71.79	2990
HSA-MIR-4761-5P	99.51	66.69	804
HSA-MIR-3123	99.47	67.15	2693
HSA-MIR-2392	99.43	67.50	708
HSA-MIR-4311	99.31	70.47	3041
HSA-MIR-892C-5P	99.16	70.56	2116
HSA-MIR-6510-5P	99.14	66.59	1081
HSA-MIR-922	99.02	67.23	1838
HSA-MIR-3619-5P	99.00	68.87	2308
HSA-MIR-876-3P	98.76	68.23	945
HSA-MIR-214-3P	98.71	68.12	2128
HSA-MIR-761	98.71	68.07	2051
HSA-MIR-6894-5P	98.70	63.78	809
HSA-MIR-3928-5P	98.50	67.48	980
HSA-MIR-6806-3P	98.50	67.31	980
HSA-MIR-4773	98.35	67.30	1710
HSA-MIR-2681-3P	98.18	65.28	577

Cross-species orthologs

0 orthologs

Paralogs (47): KRTAP4-4 (ENSG00000171396), KRTAP9-7 (ENSG00000180386), KRTAP5-5 (ENSG00000185940), KRTAP12-1 (ENSG00000187175), KRTAP10-8 (ENSG00000187766), KRTAP10-6 (ENSG00000188155), KRTAP1-1 (ENSG00000188581), KRTAP10-12 (ENSG00000189169), KRTAP4-3 (ENSG00000196156), KRTAP9-9 (ENSG00000198083), 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 9-8 — Q9BYQ0 (reviewed: Q9BYQ0)

Alternative names: Keratin-associated protein 9.8, Ultrahigh sulfur keratin-associated protein 9.8

All UniProt accessions (1): Q9BYQ0

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.

RefSeq proteins (1): NP_114169* (*=MANE)

Domains & families (InterPro)

UniProt features (19 total): repeat 15, sequence conflict 2, chain 1, region of interest 1

Structure

Experimental structures (PDB)

0 structures.

Predicted structure (AlphaFold)

Model	pLDDT	Fraction very-high
AF-Q9BYQ0-F1	39.54	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: 28 (showing top): GOCC_INTERMEDIATE_FILAMENT_CYTOSKELETON, GOCC_KERATIN_FILAMENT, GOCC_SUPRAMOLECULAR_COMPLEX, GOCC_POLYMERIC_CYTOSKELETAL_FIBER, REACTOME_KERATINIZATION, GOCC_SUPRAMOLECULAR_POLYMER, MIR570_3P, MIR494_3P, MIR892C_5P, MIR3123, MIR597_3P, MIR4468, MIR5702, MIR3605_5P, MIR6832_5P

GO Biological Process (0):

GO Molecular Function (1): protein binding (GO:0005515)

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
binding	1
cytoplasm	1
cellular anatomical structure	1
intermediate filament	1
intermediate filament cytoskeleton	1
polymeric cytoskeletal fiber	1

Protein interactions and networks

STRING

320 interactions, top by confidence (×1000):

Protein A	Protein B	Partner UniProt	Score
KRTAP9-8	KRTAP17-1	Q9BYP8	621
KRTAP9-8	KRTAP12-3	P60328	583
KRTAP9-8	KRTAP10-7	P60409	574
KRTAP9-8	KRTAP10-8	P60410	571
KRTAP9-8	OR1E2	P47887	570
KRTAP9-8	KRTAP2-3	P0C7H8	547
KRTAP9-8	OR1D5	P58170	528
KRTAP9-8	OR3A1	P47881	507
KRTAP9-8	OR3A2	P47893	507
KRTAP9-8	CD101	Q93033	487
KRTAP9-8	TMEM95	Q3KNT9	476
KRTAP9-8	C17orf50	Q8WW18	447
KRTAP9-8	OR1A2	Q9Y585	446
KRTAP9-8	TMEM220	Q6QAJ8	445
KRTAP9-8	KRTAP3-3	Q9BYR6	436

IntAct

305 interactions, top by confidence:

A	B	Type	Score
CYSRT1	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.600
LCE1A	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.600
PHLDA1	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
RGS20	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
KRTAP10-8	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
CATSPER1	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
KRTAP1-1	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
KRTAP9-8	KLHL38	psi-mi:“MI:0915”(physical association)	0.560
CREB5	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
POU4F2	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
KRTAP9-8	GNE	psi-mi:“MI:0915”(physical association)	0.560
SMCP	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
KRTAP9-8	YIPF3	psi-mi:“MI:0915”(physical association)	0.560
OTX1	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
LCE1D	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
LCE2B	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
LCE3D	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
KRTAP12-2	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
LCE3E	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
AQP1	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
KRTAP9-8	KRTAP2-4	psi-mi:“MI:0915”(physical association)	0.560
LCE1F	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
KRTAP9-8	KRTAP9-2	psi-mi:“MI:0915”(physical association)	0.560
HOXA1	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
NOTCH2NLC	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
KRTAP5-9	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
KRTAP5-11	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560
KRTAP4-1	KRTAP9-8	psi-mi:“MI:0915”(physical association)	0.560

BioGRID (100): KRTAP9-8 (Affinity Capture-MS), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid), KRTAP9-8 (Two-hybrid)

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.

Enriched among interaction partners

Reactome pathways and GO biological processes over-represented among this gene’s 82 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
Keratinization	36	32.4×	9e-46
Formation of the cornified envelope	15	21.2×	7e-15

GO biological processes:

GO term	Partners	Fold	FDR
keratinization	15	56.6×	2e-20

Disease & clinical

Clinical variants and AI predictions

ClinVar

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

Classification	Count (floor)
Pathogenic	0
Likely pathogenic	0
Uncertain significance	33
Likely benign	1
Benign	0

Top pathogenic / likely-pathogenic (0)

SpliceAI

220 predictions. Top by Δscore:

Variant	Effect	Δscore
17:41238730:A:AG	acceptor_gain	0.8200
17:41238736:T:TA	acceptor_gain	0.8000
17:41238731:C:G	acceptor_gain	0.7900
17:41238827:G:GT	donor_gain	0.7600
17:41238728:A:AG	acceptor_gain	0.7300
17:41238662:T:G	acceptor_gain	0.7200
17:41238737:G:A	acceptor_gain	0.7000
17:41238730:ACCTT:A	acceptor_gain	0.6900
17:41238108:G:GT	donor_gain	0.6800
17:41238691:G:T	donor_gain	0.6400
17:41238280:C:A	donor_gain	0.6100
17:41238729:C:G	acceptor_gain	0.6100
17:41238800:TC:T	donor_gain	0.6100
17:41238881:A:AG	acceptor_gain	0.6100
17:41238818:GCTTC:G	donor_gain	0.5800
17:41238325:C:A	donor_gain	0.5700
17:41238690:G:GT	donor_gain	0.5700
17:41238734:T:A	acceptor_gain	0.5700
17:41238760:TTCTC:T	donor_gain	0.5700
17:41238767:GTT:G	donor_gain	0.5700
17:41238768:TTT:T	donor_gain	0.5700
17:41238305:GCT:G	donor_gain	0.5600
17:41238822:C:G	donor_gain	0.5600
17:41238459:G:GT	donor_gain	0.5500
17:41238831:T:G	donor_gain	0.5500
17:41238831:T:TG	donor_gain	0.5500
17:41238474:G:GT	donor_gain	0.5400
17:41238924:T:G	acceptor_gain	0.5300
17:41238822:C:CG	donor_gain	0.5200
17:41238839:C:G	donor_gain	0.5200

AlphaMissense

1050 scored. Top likely-pathogenic:

Variant	Protein change	am_pathogenicity
17:41238364:T:C	C105R	0.741
17:41238360:A:C	R103S	0.734
17:41238360:A:T	R103S	0.734
17:41238367:T:G	Y106D	0.701
17:41238366:C:G	C105W	0.678
17:41238354:C:G	C101W	0.649
17:41238352:T:C	C101R	0.624
17:41238528:C:G	C159W	0.619
17:41238367:T:C	Y106H	0.610
17:41238526:T:C	C159R	0.600
17:41238367:T:A	Y106N	0.588
17:41238172:A:C	S41R	0.585
17:41238174:C:A	S41R	0.585
17:41238174:C:G	S41R	0.585
17:41238241:A:C	S64R	0.585
17:41238243:C:A	S64R	0.585
17:41238243:C:G	S64R	0.585
17:41238331:A:C	S94R	0.582
17:41238333:C:A	S94R	0.582
17:41238333:C:G	S94R	0.582
17:41238484:T:C	F145L	0.580
17:41238486:C:A	F145L	0.580
17:41238486:C:G	F145L	0.580
17:41238505:A:C	S152R	0.580
17:41238507:C:A	S152R	0.580
17:41238507:C:G	S152R	0.580
17:41238383:T:A	V111D	0.573
17:41238365:G:A	C105Y	0.570

dbSNP variants (sampled 300 via entrez): RS1000295991 (17:41238395 G>A), RS1001119976 (17:41238249 C>G,T), RS1002636836 (17:41237687 G>A,C), RS1003098964 (17:41237467 A>G), RS1003748641 (17:41237370 G>A), RS1003996673 (17:41237222 G>T), RS1005582527 (17:41239285 G>A), RS1005929725 (17:41237167 G>A,C), RS1006037565 (17:41237901 G>A,T), RS1006164478 (17:41236949 A>T), RS1006569202 (17:41238032 C>A), RS1007705867 (17:41239411 C>G,T), RS1009013226 (17:41236557 T>C), RS1011777785 (17:41236813 C>T), RS1012299041 (17:41237581 G>C)

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
2-methyl-4-isothiazolin-3-one	increases expression	1
clothianidin	increases expression	1
Resveratrol	affects cotreatment, decreases expression	1
Benzo(a)pyrene	increases methylation	1
Plant Extracts	affects cotreatment, decreases expression	1
Aflatoxin B1	decreases methylation	1

Clinical trials (associated diseases)

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