Cartilage oligomeric matrix protein (COMP), also known as thrombospondin-5, is an extracellular matrix (ECM) protein primarily present in cartilage. In humans it is encoded by the COMP gene.
The protein encoded by this gene is a noncollagenous extracellular matrix (ECM) protein. It consists of five identical glycoprotein subunits, each with EGF-like and calcium-binding (thrombospondin-like) domains. Oligomerization results from formation of a five-stranded coiled coil and disulfide bonds. Binding to other ECM proteins such as collagen appears to depend on divalent cations. Mutations can cause the osteochondrodysplasias pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED).