Description
β2 Glycoprotein I (β2 GP I) is a serum protein with a single polypeptide chain consisting of 326 amino acids and having a molecular weight of 50 kDa. The protein is also known by the alternative name Apolipoprotein H (ApoH) which gives an indication of its phospholipid binding function. Since the detection of β2 Glycoprotein I as a target of antiphospholipid antibodies in 1990 the discussion about the clinical relevance of β2 GP I is still controversial. It is well established that anticardiolipin antibodies are a very heterogeneous group and that β2 GP I is only one of several potential targets for anticardiolipin antibodies. Nevertheless it is generally accepted that the binding of β2 GP I to anionic lipids or surface is essential for the differential detection of anticardiolipin antibodies associated with autoimmune diseases (versus those associated with infectious diseases like syphilis, tuberculosis, AIDS, etc)