Cartilage Oligomeric Matrix Protein (COMP)

Cartilage oligomeric matrix protein (COMP) is a member of the thrombospondin family of extracellular matrix proteins. The protein consists of five 87-kDa subunits held together by interchain disulfide bonds, forming a 435-kDa pentameric protein. COMP is expressed in all types of cartilage, vitreous of the eye, tendon, and vascular smooth muscle cells.

Immunohistological staining of articular cartilage has revealed a developmentally regulated localization of COMP to the chondrocyte territorial and interterritorial matrix. COMP binds in a zinc-dependent manner to collagen type I and type II and also to collagen type IX. The thrombospondin family currently includes five members: TSP-1, TSP-2, TSP-3, TSP-4, and COMP (also referred to as TSP-5).