Collagen (胶原蛋白)

Collagens are the most abundant proteins in mammals. The collagen family comprises 28 members that contain at least one triple-helical domain. Beyond the existence of 28 collagen types, further diversity occurs in the collagen family because of the existence of several molecular isoforms for the same collagen type (e.g., collagens IV and VI) and of hybrid isoforms comprised of a chains belonging to two different collagen types (type V/XI molecules). Collagens are deposited in the extracellular matrix where most of them form supramolecular assemblies. Four collagens are type II membrane proteins that also exist in a soluble form released from the cell surface by shedding. Collagens play structural roles and contribute to mechanical properties, organization, and shape of tissues. They interact with cells via several receptor families and regulate their proliferation, migration, and differentiation^[1].