May stabilize HDL (high density lipoprotein) structure by its association with lipids, and affect the HDL metabolism. Monomer. Interacts with NAXE and NDRG1 (By similarity). Plasma. Strain C57BL/6. Without methionine sulfoxide. Strain BALB/c. Without methionine sulfoxide. Strain C57BL/6. With 1 methionine sulfoxide. Strain C57BL/6. With 2 methionine sulfoxides. Strain BALB/c. With 1 methionine sulfoxide. Strain C57BL/6. Without methionine sulfoxide. Strain BALB/c. Without methionine sulfoxide. Defects in Apoa2 are the cause of senescence accelerated mouse (SAM), the senile amyloid is a mutated apolipoprotein A-II. The apo A-II stoichiometry in HDL molecules varies among inbred mice strains, because of structural polymorphisms affecting the apo A-II gene, which influence its translational efficiency. The sequence presented here is that of strain BALB/c and C3H/HeJ. Belongs to the apolipoprotein A2 family.