Phosphorylation-dephosphorylation of apolipoprotein B

Abstract

Publisher Summary There is little doubt of the physiologic importance of apolipoprotein B (apoB). In addition to being essential for the secretion of very low-density lipoprotein (VLDL), apoB plays a fundamental role in targeting cholesterol, as a component of LDL, to tissues via specific high-affinity receptors. Although there are sufficient data demonstrating the physiological and pathophysiologic importance of apoB, little is known about its structure, sequence, and posttranslational modifications. Phosphorylation of little B is an exciting new development. The finding that phosphoserine accounts for at least 20% of the 32 P that is present in little B, whereas similar analysis of phosphatidylserine does not yield phosphoserine, strongly argues against the idea that the phosphoserine is because of contamination with phospholipid. Preliminary studies suggest that little B is poly phosphorylated, further suggesting that the phosphorylation is not an adventitious event. However, apoB is an intricate, fastidious protein and one must be cautious when interpreting results of its behavior. It is because of these problems that many are deterred from investigating apoB structure and metabolism. Yet, there is little doubt about the physiologic importance of apoB.