Physical, chemical and immunochemical characterization of a lipoprotein lipase activator protein from pig plasma very low density lipoproteins.
Very low density lipoproteins ere isolated from plasma of swine by ultracentrifugal flotation. After delipidation, the lipid-free proteins were separated by chromatography on Sephadex G-150 AND DEAE-cellulose. A major apoprotein was isolated and shown to activate cows' milk lipoprotein lipase. Since human very low density lipoproteins also contain an activator protein, designated, apoC-II, we have called the pig protein, pig apoC-II. Pig apoC-II had a molecular weight of approximately 10 000 as determined by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The amino acid composistion showed the absence of histidine, cysteine and tryptophan; there was no evidence for carbohydrate. Treatment of pig apoC-II with carboxypeptidase indicated COOH-terminal serine. Rabbit antisera prepared to the pig protein gave single precipitin lines of complete identity to very low density lipoproteins, apoC-11. Using anti-pig apoC-II, a radioimmunoassay was developed which provides a convenient and reproducible method for measuring 5-1000 ng of apoprotein.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001053:Apolipoproteins / Q000502:physiology; D004789:Enzyme Activation; D005779:Immunodiffusion; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008079:Lipoproteins, VLDL / Q000097:blood / Q000502:physiology; D008892:Milk / Q000201:enzymology; D008970:Molecular Weight; D011863:Radioimmunoassay; D013552:Swine
D000596:Amino Acids; D001053:Apolipoproteins; D008079:Lipoproteins, VLDL; D008071:Lipoprotein Lipase