Keratin 5 Keratin 5 Keratin 5, also known as KRT5, K5, or CK5, is a protein that is encoded in humans by the "KRT5" gene. It dimerizes with keratin 14 and forms the intermediate filaments (IF) that make up the cytoskeleton of basal epithelial cells. This protein is involved in several diseases including epidermolysis bullosa simplex and breast and lung cancers. Keratin 5, like other members of the keratin family, is an intermediate filament protein. These polypeptides are characterized by a 310 residue central rod domain that consists of four alpha helix segments (helix 1A, 1B, 2A, and 2B) connected by three
Alpha-keratin large variation in α-keratin structures found in mammals. α-keratin synthesis begins near focal adhesions on the cell membrane. There, the keratin filament precursors go through a process known as nucleation, where the keratin precursors of dimers and filaments elongate, fuse, and bundles together. As this synthesis is occurring, the keratin filament precursors are transported by actin fibers in the cell towards the nucleus. There, the alpha-keratin intermediate filaments will collect and form networks of structure dictated by the use of the keratin cell as the nucleus simultaneously degrades. However, if necessary, instead of continuing to grow, the keratin complex will