Alternative titles; symbolsK27KRT25C; K25CKA40K10BKERATIN 25, INNER ROOT SHEATH, 3; KRT25IRS3; K25IRS3IRSA3.1CYTOKERATIN 27; CK27HGNC Approved Gene Symbol: KRT27...
Alternative titles; symbols
HGNC Approved Gene Symbol: KRT27
Cytogenetic location: 17q21.2 Genomic coordinates (GRCh38): 17:40,776,807-40,782,549 (from NCBI)
Keratins are structural proteins that form the intermediate filament cytoskeleton in all epithelia. They assemble into long filaments built from heterodimeric double-stranded coils of type I and type II keratins. KRT27 is a type I keratin of hair inner root sheath Hesse et al. (2004).
▼ Cloning and Expression
By database analysis and RT-PCR of a human scalp cDNA library, Rogers et al. (2004) cloned KRT27, which they called K25IRS3. The deduced 459-amino acid protein has a calculated molecular mass of 49.8 kD and contains a long central alpha-helical region. RT-PCR detected K25IRS3 expression in skin and scalp, but not in tongue, thymus, breast, placenta, or eye.
By in situ hybridization and immunohistochemical analysis of human hair follicle, Langbein et al. (2006) found that K27 was expressed in the Henle layer, the Huxley layer, and the inner root sheath cuticle. Expression extended from the bulb region to the points of terminal differentiation in these 3 layers. K27 was also expressed in hair medulla.
▼ Gene Structure
Rogers et al. (2004) reported that the KRT27 gene has 8 exons.
By genomic sequence analysis, Hesse et al. (2004) mapped the KRT27 gene to the keratin I gene cluster on chromosome 17q21.2. The mouse Krt27 gene is located in a keratin I cluster in a region of chromosome 11D that shares homology of synteny with human chromosome 17q21.
Schweizer et al. (2006) provided an updated nomenclature for keratins. They noted that KRT27 had previously been called K25IRS3, K10B, IRSA3.1, KRT25C, and KA40.