Characterization of human very low density lipoproteins containing two electrophoretic populations: double pre-beta lipoproteinemia and primary dysbetalipoproteinemia

Abstract

Two discrete populations of very low density lipoproteins, with fast and slow pre-beta electrophoretic mobility, were found in 50% of normolipemic and 30% of hyperlipemic individuals selected at random. The two populations were isolated by preparative electrophoresis from five hyperlipemic subjects. The particles comprising the slow component were smaller than those of the fast component and the slow component contained a larger proportion of cholesteryl esters, free cholesterol, B-apoprotein, and arginine-rich apoprotein and a smaller proportion of triglycerides and the two most anionic apoproteins (R-glutamic acid and R-alanine). The properties of the slow component thus closely resemble those of "remnant" very low density lipoproteins that accumulate in blood plasma of functionally hepatectomized rats. The chemical composition of the slow component was also similar to that of the very low density lipoproteins with beta mobility found in primary dysbetalipoproteinemia. However, the proportion of cholesteryl esters and argininerich apoprotein was much higher in the latter. The argininerich apoprotein from very low density lipoproteins of most normolipemic and hyperlipemic subjects separates into three or four major bands upon isoelectric focusing electrophoresis in polyacrylamide gels, with pI varying from 5.57 to 6.03. In very low density lipoproteins from individuals with primary dysbetalipoproteinemia, this protein uniquely contains little or none of the two most cationic bands. The number of bands was constant in all subjects studied. The pattern was the same in very low density lipoproteins with fast and slow pre-beta mobility as well as in the beta and pre-beta components in primary dysbetalipoproteinemia. These results suggest that many individuals have "remnant" very low density lipoproteins in their plasma. However, the beta-migrating "remnant" that accumulated in large amounts in individuals with primary dysbetalipoproteinemia contains much more arginine-rich protein and this protein is structurally abnormal.