Collagen receptor

Collagen receptors are membrane proteins that bind the extracellular matrix protein collagen, the most abundant protein in mammals. . They may enable adhesion between cells and/or propagate signals into the cell.

There are at least eight human collagen receptors. Several of these are Integrin receptors. Integrin α1β1 is a heterodimer of large α and β subunits; collagen binds to the MIDAS motif in the α subunit I domain. It preferentially binds collagens IV and VI, but also fibril-forming collagens. Specific binding sites in collagen I and IV have been identified. Functions include: fibroblast proliferation; regulation of collagen synthesis and MMP expression; response to renal injury. Integrin α2β1 has a structure similar to Integrin α1β1. It preferentially binds fibril-forming collagens. Specific binding sites in collagen I and III have been identified. Functions include: platelet adhesion - the most abundant receptor for collagen in platelets; branching morphogenesis; mast cell activation; keratinocyte adhesion.

Integrin α10β1 structure as above. Preferentially binds collagens IV and VI, but also collagen II. Involved in growth plate morphogenesis and function. Integrin α11β1 structure as above. Preferentially binds fibril-forming collagens; specific sites in collagen I identified. Functions are not well defined.

DDR1 is a homodimer. It's ectodomain consists of a collagen-binding discoidin domain followed by ~200 residues of unknown structure. It binds fibril-forming collagens and collagen IV, collagen VIII. Functions include: mammary gland development; arterial wound repair; regulation of cell proliferation and MMP expression; kidney function, differentiation and function of leukocytes.

DDR2 structure as above. Binds fibril-forming collagens, collagen X. A specific binding site in collagen II has been identified. Functions include: Chondrocyte proliferation and bone growth; regulation of cell proliferation and MMP expression.

Glycoprotein VI is a heterotetramer with the FcRγ chain. It’s ectodomain contains two IG domains, the first of which binds collagen. It binds fibril-forming collagens; and the synthetic collagen peptide (GPO)10. Functions include: Platelet adhesion and activation - the most important platelet collagen receptor in terms of signaling. LAIR1 has an ectodomain that consists of a single IG domain. It binds fibril-forming collagens and (GPO)10. It is involved in immune cell regulation.

Mannose receptor family (MR, PLA2R, DEC-205, Endo180, uPARAP). These have a large ectodomain consisting of cysteine-rich domain, a collagen-binding F2 domain, and eight to ten C-type lectin domains. Binds fibril-forming collagens and collagen IV, as well as gelatin.