Dictionary.net

Lipoproteins found in human blood serum in the high-density and very-high-density lipoprotein fraction (HDL; VHDL). They consist of several different polypeptides, the most important of which are apolipoprotein A-I and A-II. They maintain the structural integrity of the HDL particles and are activators of lecithin:cholesterol acyltransferase (LCAT). Atherosclerotic patients show low apolipoprotein A levels and these apolipoproteins are either absent or present in extremely low plasma concentration in TANGIER DISEASE.