The impact of phospholipid transfer protein (PLTP) on HDL metabolism

High-density lipoproteins (HDL) play a major protective role against the de velopment of coronary artery disease. Phospholipid transfer protein (PLTP) is a main factor regulating the size and composition of HDL in the circulat ion and plays an important role in controlling plasma HDL levels. This is a chieved via both the phospholipid transfer activity of PLTP and its capabil ity to cause HDL conversion. The present review focuses on the impact of PL TP on HDL metabolism. The basic characteristics and structure of the PLTP p rotein are described. The two main functions of PLTP, PLTP-mediated phospho lipid transfer acid HDL conversion are reviewed, and the mechanisms and con trol, as well as the physiological significance of these processes are disc ussed. The relationship between PLTP and the related cholesteryl ester tran sfer protein (CETP) is reviewed. Thereafter other functions of PLTP are rec apitulated: the: ability of PLTP to transfer cholesterol, alpha -tocopherol and lipopolysaccharide (LPS). and the suggested involvement of PLTP in cel lular cholesterol traffic. The discussion on PLTP activity and mass in (pat ho)physiological settings includes new data on the presence of two forms of PLTP in the circulation, one catalytically active and the other inactive. Finally. future directions for PLTP research are outlined. (C) 2001 Elsevie r science Ireland Ltd. All rights reserved.