Apoprotein C metabolism in man.

Abstract

This chapter focuses on apoprotein C metabolism in man. The C apoprotein (apoC) group is closely linked to triglyceride metabolism, and the identification of one peptide, later called apoC-II, as the activator of lipoprotein lipase represented the first demonstration of a specific function for an apoprotein. Human lipoproteins have generally been preferred for in vitro experiments, and probably more has been learned from the metabolic investigations carried out in humans than in experimental animals. In the presence of plasma, it is evident that apoC species exchange between VLDL and HDL. Although apoC has also been found in lipoprotein—free fractions when released from VLDL in the absence of serum or HDL, this does not mean that they will exist in this form under physiological conditions. Furthermore, the very marked affinity of apoC for phospholipids at physiological temperatures would suggest that, even if liberated as pure apoproteins, they would mostly bind to lipoproteins where phospholipids are present in an ordered surface structure such as HDL.