Keratin 40 is an alias for the gene, Keratin 40, type I, in humans. Other names include: Keratin, type I cytoskeletal 40; Cytokeratin-40; CK-40; Keratin-40; K40; Type I hair keratin Ka36; KA36. The encoded protein has an amino acid length of 431 and a mass of 48.1 kDa. Keratin 40 is a member of the Intermediate filament family. This gene shares homology with other species, including: Mouse, Rat.