Plasma lipid transport.
The main plasma lipid transport forms are free fatty acid, triglyceride and cholesteryl ester. Free fatty acid, derived primarily from adipocyte triglycerides, is transported as a physical complex with plasma albumin. Triglycerides and cholesteryl esters are transported in the core of plasma lipoproteins. The intestine secretes dietary fat in chylomicrons, lipoproteins that transport triglyceride to tissues for storage. Dietary cholesterol is transported to the liver by chylomicron remnants which are formed from chylomicrons. Triglyceride is released from the liver in very low density lipoproteins for utilization and storage in extrahepatic tissues. Very low density lipoproteins are converted to low density lipoproteins in the plasma; in the process, they become enriched in cholesteryl esters. High density lipoproteins take up cholesterol from tissues and other plasma lipoproteins. After the cholesterol is esterified, it is transferred ultimately to low density lipoproteins for uptake by the tissues. Phospholipids are structural components of lipoproteins and provide fatty acid for cholesteryl ester formation in the plasma, but they are not a primary transport form of lipid. Six enzymes, together with apolipoprotein cofactors and lipid transfer proteins, facilitate the plasma lipid transport process.
D000418:Albumins / Q000378:metabolism; D001693:Biological Transport, Active; D002784:Cholesterol / Q000097:blood / Q000378:metabolism; D002788:Cholesterol Esters / Q000097:blood / Q000378:metabolism; D005227:Fatty Acids / Q000097:blood; D005230:Fatty Acids, Nonesterified / Q000097:blood / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D008055:Lipids / Q000097:blood*; D008099:Liver / Q000378:metabolism; D010743:Phospholipids / Q000097:blood / Q000378:metabolism; D014280:Triglycerides / Q000097:blood / Q000378:metabolism
D000418:Albumins; D002788:Cholesterol Esters; D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D008055:Lipids; D010743:Phospholipids; D014280:Triglycerides; D002784:Cholesterol