Sandbox 215: Difference between revisions
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== Mechanism allowing neutral-lipid and phospholipid transfer == | == Mechanism allowing neutral-lipid and phospholipid transfer == | ||
In the plasma circulation, CETP often binds HDL and engages the tranfer of neutral lipids, such as cholesteryl ester and triglyceride among lipoprotein particles. The concave structure of CETP | In the plasma circulation, CETP often binds high density lipoproteins (HDL) and engages the tranfer of neutral lipids, such as cholesteryl ester and triglyceride among lipoprotein particles. The concave structure of CETP is the only surface able to bind a lipoprotein. Other surfaces of CETP are not able to bind them. It indicates that CETP can bind only one lipoprotein at a time. It means that CETP operates as carrier: CETP accepts neutral lipids from a donor particule and releases them to an acceptor particule. | ||
Binding to a HDL particle, which is cholesteryl ester rich, allows CETP to fill with cholesteryl esters, because one or two cholesteryl esters can enter the tunnel and an equal amount of triglyceride is deposited into HDL. Then the tunnel is refilled with two phospholipid (one at each end) that permits the protein to dissociate from HDL and to retunr to the acqueous phase. CETP also adopts a structural change by twisting its barrel around the central β-sheet in order to bind VLDL particules which are larger than HDL particules. Binding to a VLDL particle, which is triglyceride rich, permits the release of the bound phospholipid. That allows one or two triglycerides to enter the tunnel and an equal amount of cholesteryl ester can be deposit into VLDL. The triglyceride-bound dissociates from VLDL. It carries two phospholipids from the surface of VLDL and travels through the acqueous plasma in order to rebind a HDL particle. Binding to a HDL particle, permits the release of the bound phospholipid and the cycle can continue. | Binding to a HDL particle, which is cholesteryl ester rich, allows CETP to fill with cholesteryl esters, because one or two cholesteryl esters can enter the tunnel and an equal amount of triglyceride is deposited into HDL. Then the tunnel is refilled with two phospholipid (one at each end) that permits the protein to dissociate from HDL and to retunr to the acqueous phase. CETP also adopts a structural change by twisting its barrel around the central β-sheet in order to bind VLDL particules which are larger than HDL particules. Binding to a VLDL particle, which is triglyceride rich, permits the release of the bound phospholipid. That allows one or two triglycerides to enter the tunnel and an equal amount of cholesteryl ester can be deposit into VLDL. The triglyceride-bound dissociates from VLDL. It carries two phospholipids from the surface of VLDL and travels through the acqueous plasma in order to rebind a HDL particle. Binding to a HDL particle, permits the release of the bound phospholipid and the cycle can continue. | ||
