ApoAI (Apolipoprotein A1) is a major component of high density lipoprotein (HDL, the ''good cholesterol) in plasma. It is produced in the liver and small intestine. ApoA1 is a cofactor for lecithin cholesterolacyltransferase (LCAT) that is responsible for the formation of plasma cholesteryl esters and promotes cholesterol efflux from tissues to the liver for excretion.