KRT39 (Keratin 39)
Type I Cytoskeletal Keratin 39: Structure, Expression, and Clinical Relevance
Gene Information Card
| Symbol | KRT39 |
|---|---|
| Full Name | Keratin 39 |
| Gene Type | Protein coding |
| Chromosomal Location | 17q21.2 |
| NCBI Gene ID | 390792 ncbi.nlm.nih.gov/gene/390792 |
| Ensembl ID | ENSG00000198947 |
| UniProt ID | Q7Z3Z0 |
| OMIM ID | 616878 |
| HGNC ID | 28186 |
| Aliases | KA35, KRT35, K39, hK39 |
Description
KRT39 encodes keratin 39, a type I intermediate filament protein (acidic keratin) primarily expressed in hair and nail tissues. It forms heterodimers with type II keratins to provide structural integrity to epithelial cells. Mutations in KRT39 are associated with ectodermal dysplasias and hair disorders.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Ectodermal dysplasia 7, hair/nail type | Missense mutations disrupt keratin filament assembly | OMIM #616878 |
| Woolly hair, autosomal recessive | Loss-of-function variants impair hair shaft structure | ClinVar |
| Monilethrix (beaded hair) | Pathogenic variants in helix initiation motif | NCBI Gene |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Skin | 0.0 | Not detected |
| Hair follicle | High | High |
| Nail | High | High |
| Tongue | 0.0 | Not detected |
| Esophagus | 0.0 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HaCaT (keratinocyte) | 0.0 | Not expressed |
| NHEK (normal human epidermal keratinocytes) | 0.0 | Not expressed |
| Hair follicle dermal papilla cells | High | Expressed |
| Nail matrix keratinocytes | High | Expressed |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.334C>T (p.Arg112Cys) | Missense | Rare | Disrupts helix initiation motif, causes woolly hair |
| c.371G>A (p.Arg124His) | Missense | Rare | Associated with ectodermal dysplasia 7 |
| c.2T>C (p.Met1Thr) | Start loss | Very rare | Loss of function, monilethrix phenotype |
Mutation functional classification
Loss of Function (LOF)
Start loss and nonsense variants lead to haploinsufficiency, causing hair shaft fragility.
Gain of Function (GOF)
Not reported for KRT39.
Dominant Negative (DN)
Missense mutations in helix initiation motif act as dominant-negative, disrupting filament assembly.
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) |
| • epidermis development (GO:0008544) |
Pathways
• Intermediate filament organization (Reactome: R-HSA-6809371)
• Keratinization (Reactome: R-HSA-6805567)
Protein Summary
Keratin 39 is a 55 kDa type I acidic keratin expressed specifically in hair and nail epithelia. It forms obligate heteropolymers with type II keratins (e.g., KRT81, KRT83) to build intermediate filaments essential for mechanical resilience. The protein contains a central alpha-helical rod domain with conserved helix initiation and termination motifs. Mutations in these motifs cause structural defects leading to hair and nail disorders.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| KRT39 Knockout HEK293 Cell Line | EDJ-KQ13977 | Human | 390792 | Details Get a Quote |
| KRT39 Knockout HeLa Cell Line | EDJ-KQ60192 | Human | 390792 | Details Get a Quote |
| KRT39 Knockout A-549 Cell Line | EDJ-KQ68654 | Human | 390792 | Details Get a Quote |
| KRT39 Knockout HCT 116 Cell Line | EDJ-KQ77022 | Human | 390792 | Details Get a Quote |
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