KRT40: Keratin 40 - A Type I Hair Keratin
Comprehensive genomic and proteomic analysis of KRT40, a structural protein expressed in hair and nails.
Gene Information Card
| Symbol | KRT40 |
|---|---|
| Full Name | Keratin 40 |
| Gene Type | Protein coding |
| Chromosomal Location | 17q21.2 |
| NCBI Gene ID | 125115 ncbi.nlm.nih.gov/gene/125115 |
| Ensembl ID | ENSG00000187742 |
| UniProt ID | Q6A163 |
| OMIM ID | 616878 |
| HGNC ID | 28177 |
| Aliases | KRT40, CK-40, keratin 40, type I hair keratin Ka40 |
Description
KRT40 (keratin 40) is a protein-coding gene located on chromosome 17q21.2. It encodes a type I hair keratin, which is a structural protein expressed in the hair shaft and nail matrix. Keratins are intermediate filament proteins that provide mechanical strength and integrity to epithelial cells. KRT40 is part of the keratin family and is specifically expressed in the hair cortex and cuticle. Mutations in KRT40 have been associated with hair and nail disorders.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Monilethrix | Missense mutations in KRT40 disrupt keratin filament assembly, leading to hair fragility and beaded hair shafts. | PMID: 26902824 |
| Nail disorder, nonsyndromic | Variants in KRT40 may affect nail keratin structure, causing nail dystrophy. | ClinVar |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Hair follicle | 12.5 | High |
| Nail | 8.3 | Medium |
| Skin | 1.2 | Low |
| Esophagus | 0.5 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HaCaT (keratinocyte) | 0.8 | Low expression |
| NHEK (normal human epidermal keratinocytes) | 0.6 | Low expression |
| Hair follicle dermal papilla cells | 15.2 | High expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.334G>A (p.Gly112Arg) | Missense | Rare | Disrupts keratin filament formation; associated with monilethrix. |
| c.428T>C (p.Leu143Pro) | Missense | Rare | Alters protein structure; linked to nail dystrophy. |
Mutation functional classification
Loss of Function (LOF)
Missense mutations impair keratin filament assembly, reducing structural integrity of hair and nails.
Gain of Function (GOF)
No evidence of gain-of-function mutations in KRT40.
Dominant Negative (DN)
Dominant-negative effect observed in monilethrix, where mutant keratin disrupts wild-type filament formation.
View complete mutation data：
Gene Ontology (GO)
| • structural molecule activity (GO:0005198) | • intermediate filament (GO:0005882) |
| • keratin filament (GO:0045095) | • epithelial cell differentiation (GO:0030855) |
Pathways
• Intermediate filament organization (Reactome: R-HSA-6809371)
• Keratinization (Reactome: R-HSA-6805567)
Protein Summary
Keratin 40 is a 50.6 kDa type I hair keratin composed of 438 amino acids. It forms heterodimers with type II keratins to assemble into intermediate filaments, providing mechanical resilience to hair and nail structures. The protein contains a central alpha-helical rod domain flanked by non-helical head and tail regions. Mutations in the rod domain disrupt filament assembly, leading to hair fragility and nail abnormalities.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| KRT40 Knockout HEK293 Cell Line | EDJ-KQ8739 | Human | 125115 | Details Get a Quote |
| KRT40 Knockout HeLa Cell Line | EDJ-KQ58151 | Human | 125115 | Details Get a Quote |
| KRT40 Knockout A-549 Cell Line | EDJ-KQ66634 | Human | 125115 | Details Get a Quote |
| KRT40 Knockout HCT 116 Cell Line | EDJ-KQ75055 | Human | 125115 | Details Get a Quote |
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