Tranfer of Triglyceride Between Lipoproteins by a Protein Complex Isolated from Lipid-Free Plasma
Pickford, Laura A,
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Human plasma was found to contain a lipid transfer complex (LTC) in the density>1.21 g/ml infranatant which facilitated the transfer of cholesteryl esters, phosphatidylcholine and triglyceride between lipoproteins. Triglyceride transfer occured between very low density lipoproteins (VLDL) and low density lipoproteins (LDL), but there was no reciprcal transfer of cholesteryl ester. Triglyceride transfer also occured between VLDL and HDL and there was a reciprocal transfer of cholesteryl ester. Parachloromercuryphenyl sulfonate (PCMPS) inhibited triglyceride transfer from VLDL to LDL and HDL, however it did not inhibit cholesteryl ester transfer from HDL to VLDL. These data suggested that the LTC contains two transfer proteins, one for triglyceride and one for cholesteryl ester,or one protein with two different active sites, one of which was inhibited by PCMPS. The effects of triglyceride transfer between VLDL and LDL on the catabolism of VLDL were tested in an in vitro assay containing bovine milk lipoprotein lipase and albumin. The transfer of triglyceride to LDL and HDL was accompanied by a decrease in the rate of VLDL catabolism.