Seroatlas · Human Serome Atlas

KRT9

Keratin, type I cytoskeletal 9

Also known as: CK-9, EPPK, K1C9_HUMAN, K9

Cross-references: UniProt · Ensembl · Human Protein Atlas · GeneCards · NCBI Gene

Protein identityUniProt · HPA

UniProt accession
P35527
Gene
KRT9
Ensembl
ENSG00000171403
Chromosome
17
Canonical length
623 aa
Protein class
Disease related genes, Human disease related genes, Plasma proteins, Predicted intracellular proteins

OverviewNCBI Gene

This gene encodes the type I keratin 9, an intermediate filament chain expressed only in the terminally differentiated epidermis of palms and soles. Mutations in this gene cause epidermolytic palmoplantar keratoderma. [provided by RefSeq, Jul 2008]

Canonical amino-acid sequenceUniProt

623 residues, UniProt reviewed canonical sequence.

>P35527|KRT9
     1  MSCRQFSSSY LSRSGGGGGG GLGSGGSIRS SYSRFSSSGG GGGGGRFSSS SGYGGGSSRV
    61  CGRGGGGSFG YSYGGGSGGG FSASSLGGGF GGGSRGFGGA SGGGYSSSGG FGGGFGGGSG
   121  GGFGGGYGSG FGGFGGFGGG AGGGDGGILT ANEKSTMQEL NSRLASYLDK VQALEEANND
   181  LENKIQDWYD KKGPAAIQKN YSPYYNTIDD LKDQIVDLTV GNNKTLLDID NTRMTLDDFR
   241  IKFEMEQNLR QGVDADINGL RQVLDNLTME KSDLEMQYET LQEELMALKK NHKEEMSQLT
   301  GQNSGDVNVE INVAPGKDLT KTLNDMRQEY EQLIAKNRKD IENQYETQIT QIEHEVSSSG
   361  QEVQSSAKEV TQLRHGVQEL EIELQSQLSK KAALEKSLED TKNRYCGQLQ MIQEQISNLE
   421  AQITDVRQEI ECQNQEYSLL LSIKMRLEKE IETYHNLLEG GQEDFESSGA GKIGLGGRGG
   481  SGGSYGRGSR GGSGGSYGGG GSGGGYGGGS GSRGGSGGSY GGGSGSGGGS GGGYGGGSGG
   541  GHSGGSGGGH SGGSGGNYGG GSGSGGGSGG GYGGGSGSRG GSGGSHGGGS GFGGESGGSY
   601  GGGEEASGSG GGYGGGSGKS SHS

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against KRT9 can act on the native protein depends on physical access: surface and secreted proteins are reachable by circulating antibodies, intracellular proteins usually are not.

Antibody reachability
Secreted
Secreted
Yes
Transmembrane segments
0
Mean surface accessibility (rSASA)
0.62
Highest tissue expression
11 nTPM

Expression across tissuesHPA

Tissue

  • thymus: 11 nTPM
  • skin: 2.3 nTPM
  • adrenal gland: 0.5 nTPM
  • vagina: 0.3 nTPM
  • breast: 0.2 nTPM
  • esophagus: 0.2 nTPM

Single-cell type

  • adrenal medulla cells: 11 nCPM
  • breast myoepithelial cells: 7.7 nCPM
  • extravillous trophoblasts: 3.3 nCPM
  • basal keratinocytes: 2.5 nCPM
  • salivary myoepithelial cells: 1.9 nCPM
  • ocular epithelial cells: 1 nCPM

Immune cell

  • basophil: 0 nTPM
  • classical monocyte: 0 nTPM
  • eosinophil: 0 nTPM
  • gdT-cell: 0 nTPM
  • intermediate monocyte: 0 nTPM
  • MAIT T-cell: 0 nTPM

Brain region

  • spinal cord: 0.2 nTPM
  • midbrain: 0.1 nTPM
  • amygdala: 0 nTPM
  • basal ganglia: 0 nTPM
  • cerebellum: 0 nTPM
  • cerebral cortex: 0 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about KRT9.

Disease | AllUniProt

Conditions KRT9 is implicated in, by any mechanism.

  • Palmoplantar keratoderma, epidermolytic, 1 (EPPK1) MIM:144200

Disease | GeneticClinVar

19 pathogenic / likely-pathogenic of 238 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

Genetic constraint and essentialitygnomAD · DepMap

Does the body need this protein intact? Low LOEUF or a strong DepMap dependency means loss or blockade of the protein is likely to be felt.

gnomAD LOEUF (loss-of-function intolerance)
0.92
gnomAD pLI
0
gnomAD missense Z
0.2
DepMap mean gene effect
-0.1
DepMap dependency class
selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 2% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads KRT9 as an antibody target. Whether an autoantibody or antibody against KRT9 could matter depends on whether native KRT9 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

KRT9 is annotated as secreted, so native KRT9 circulates and is directly accessible to antibodies. Secreted and cell-surface proteins are the autoantibody targets most likely to act like drugs, blocking or depleting the native protein.

Annotation status

The present source text does not explicitly label KRT9 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/KRT9. Study-independent annotations aggregated from UniProt, Human Protein Atlas, PubMed, IEDB, Pfam, InterPro, Gene Ontology, AlphaFold, gnomAD, DepMap, ClinVar, TCGA. Catalog release seroatlas-reviewed-human-uniprot-20260313.

Seroatlas is the reference for exploring autoantibody and antibody serology at the human-protein level: the autoreactome and human serome, multiplex serology (HuProt, HuScan, VirScan, PhIP-Seq).

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