The apolipoproteins are a structurally-unrelated group of proteins that have some association with the transport of lipids in blood. Apolipoproteins, together with phospholipids, cholesterol and triglycerides, form spherical particles with a lipid/hydrophobic center and a apolipoprotein coat. The apolipoprotein coat promotes aqueous solubility and serves as a ligand for lipoprotein receptors. HDL may contain apolipoproteins A, C, D, E, J, L and M, while LDL contains apolipoproteins B and E. ApoA2 (Apolipoprotein A-II, ApoA-II, ApoA-2) is a major component of high density lipoprotein (HDL) and it plays an important role in directing the fate of lipid metabolism among HDL. Defects in the gene may result in ApoA2 deficiency or hypercholesterolemia. It is primarily synthesized by liver. The predicted MW of ApoA2 is 11 kDa, while the mature form is smaller (7-10 kDa) since the signal peptide was cleaved. In humans, most of circulating ApoA2 exist as dimer. Five types of ApoA2 dimer exist: homodimer ApoA2-ATQ/ATQ, heterodimer ApoA2-ATQ/AT, homodimer ApoA2-AT/AT, ApoA2-AT/A, and ApoA2-A/A. ApoA2 isoforms are considered to be some of the most promising serum/plasma biomarkers for aiding the early detection of pancreatic cancer.