Cytokeratin 17 (CK17)

Keratin 17 is found in nail beds, hair follicles, sebaceous glands, and other epidermal appendages. Mutations in the gene encoding this protein lead to Jackson-Lawler type pachyonychia congenita and steatocystoma multiplex.The functional KRT17 gene differs from the pseudogenes by the extent of methylation of certain DNA sequences in the 5-prime upstream region. The KRT17 gene encodes a polypeptide of 432 amino acids with a calculated molecular weight of 48,000. Using S1-nuclease protection assays and RNAs from several cell lines, Troyanovsky et al. identified a single transcriptional start point 26 nucleotides downstream from a TATA box element. Synthesis of cytokeratin-17 seems to be a marker of basal cell differentiation in complex epithelia and therefore indicative of a certain type of epithelial 'stem cell.'