Apolipoprotein H (APOH)

Apolipoprotein H (ApoH), also known as Beta 2-glycoprotein I, is a plasma glycoprotein either circulating as a free protein or associated to lipoproteins. This protein was found in human serum and described for the first time in 1961 by Schultze et al. ApoH is a 54-kDa single-chain glycoprotein consisting of five carbohydrate chains and 326 amino acid residues that can be divided into five short consensus repeat domains.

ApoH has been chiefly focused on as the cofactor or autoantigen in antiphospholipid syndrome (APS), which is related to venous and arterial thrombosis, fetal loss, and thrombocytopenia. Reports show that ApoH may have an important function in blood coagulation and clearance of apoptotic bodies from the circulation.