APOA2 stabilizes the HDL structure by its relationship with lipids,and plays a role in the HDLMetabolism. APOA2 is the 2nd most abundant protein of the high density lipoprotein particles. APOA2 is localized in plasma as a monomer,homodimer,or heterodimer with apolipoprotein D. Defects in APOA2 gene might cause apolipoprotein A-II deficiency or hypercholesterolemia.