Major Apoproteins and Enzymes Important to Lipid Metabolism
Component | Location | Function |
|---|---|---|
Apoproteins | ||
Apo A-I | HDL | Major component of HDL particle |
Apo A-II | HDL | Component of HDL particle |
Apo A-V | HDL (primarily), VLDL, chylomicrons | LPL cofactor for lipolysis of TGs |
Apo B-100 | VLDL, IDL, LDL, Lp(a) | LDL receptor ligand |
Apo B-48 | Chylomicrons | Major component of chylomicron |
Apo C-II | Chylomicrons, VLDL, HDL | LPL cofactor |
Apo C-III | Chylomicrons, VLDL, HDL | Inhibits LPL |
Apo E | Chylomicrons, remnants, VLDL, HDL | LDL receptor ligand |
Apo(a) | Lp(a) | Component of Lp(a) and links to LDL-like particle |
Enzymes | ||
ABCA1 | Within cells | Contributes to intracellular cholesterol transport to membrane |
CETP | HDL | Mediates transfer of cholesteryl esters from HDL to VLDL |
LPL | Endothelium | Hydrolyzes triglycerides of chylomicrons and VLDL to release free fatty acids |
LCAT | HDL | Esterifies free cholesterol for transport within HDL |
ABCA1 = ATP-binding cassette transporter A1; apo = apoprotein; CETP = cholesteryl ester transfer protein; HDL = high-density lipoprotein; IDL = intermediate-density lipoprotein; LCAT = lecithin-cholesterol acyltransferase; LDL = low-density lipoprotein; LPL = lipoprotein lipase; Lp(a) = lipoprotein (a); TG = triglycerides; VLDL = very-low-density lipoprotein. | ||