Apolipoprotein H

Apolipoprotein H (Apo-H), previously known as (β₂-glycoprotein I, beta-2 glycoprotein I), is a 38 kDa multifunctional apolipoprotein that in humans is encoded by the APOH gene. One of its functions is to bind cardiolipin. When bound the structure of cardiolipin and Apo-H 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).