Collagen, type XVII, alpha 1 Collagen, type XVII, alpha 1 Collagen XVII, previously called BP180, is a transmembrane protein which plays a critical role in maintaining the linkage between the intracellular and the extracellular structural elements involved in epidermal adhesion. Collagen XVII is a homotrimer of three alpha1(XVII)-chains and a transmembrane protein in type II orientation. Each 180 kD a-chain contains a globular intracellular domain of approximately 70 kDa, which interacts with beta4-integrin, plectin, and BP230 and is necessary for the stable attachment of hemidesmosomes to keratin intermediate filaments. The large C-terminal ectodomain with a molecular mass of approximately 120 kDa consists of 15 collagenous
Keratin 5 heterodimers are formed between specific pairs of type I (acidic) and type II (basic) keratin. K5, a type II keratin, pairs with the type I keratin K14. The coiled-coil dimers undergo stepwise assembly and combine in an antiparallel manner, forming end-to-end interactions with other coiled-coils to form large 10 nm intermediate filaments. Keratin 5 (and K14) are expressed primarily in basal keratinocytes in the epidermis, specifically in the stratified epithelium lining the skin and digestive tract. Keratin intermediate filaments make up the cytoskeletal scaffold within epithelial cells, which contributes to the cell architecture and provides the cells with the ability