APOH
Description
The APOH (apolipoprotein H) is a protein-coding gene located on chromosome 17.
β2-glycoprotein 1, also known as beta-2 glycoprotein 1 and Apolipoprotein H (Apo-H), is a 38 kDa multifunctional plasma protein that in humans is encoded by the APOH gene. One of its functions is to bind cardiolipin. When bound, the structure of cardiolipin and β2-GP1 both undergo large changes in structure. Within the structure of Apo-H is a stretch of positively charged amino acids (protein sequence positions 282-287), Lys-Asn-Lys-Glu-Lys-Lys, are involved in phospholipid binding (see image on right). β2-GP1 has a complex involvement in agglutination. It appears to alter adenosine diphosphate (ADP)-mediated agglutination of platelets. Normally, β2-GP1 assumes an anticoagulation activity in serum (by inhibiting coagulation factors); however, changes in blood factors can result in a reversal of that activity. Although previously referred to as apolipoprotein H, it is not present in appreciable quantities in the lipoprotein fractions, so ApoH is therefore thought to be a misnomer. β2-GP1 appears to completely inhibit serotonin release by the platelets and prevents subsequent waves of the ADP-induced aggregation. The activity of β2-GP1 appears to involve the binding of agglutinating, negatively charged compounds, and inhibits agglutination by the contact activation of the intrinsic blood coagulation pathway.
APOH is also known as B2G1, B2GP1, BG.
