60] Phospholipid transfer proteins from yeast

Abstract

This chapter discusses the phospholipid transfer proteins from yeast. Baker's yeast, Saccharomyces cerevisiae , contains at least two cytosolic proteins, which catalyze transport of phospholipids between natural membranes and phospholipid vesicles in vitro. One protein is specific for phosphatidylinositol (Ptdlns) and phosphatidylcholine (PtdCho) and closely resembles Ptdlns-transfer protein from mammalian tissues with respect to size, isoelectric point, substrate specificity, and inhibition by negatively charged phospholipids. The second yeast phospholipid transfer protein has a broad substrate specificity in that it catalyzes preferentially the transfer ofphosphatidylserine (PtdSer) as well as phosphatidylethanolamine (PtdEtn), cardiolipin, phosphatidic acid, and ergosterol. In contrast to the mammalian nonspecific lipid transfer protein, the yeast protein does not mediate intermembrane movement of PtdIns or PtdCho. Yeast is considered a useful biological model to study the role of proteins in vivo by a combination of biochemical and molecular genetics techniques. Recent experiments have revealed that the PtdIns transfer protein is essential for cellular growth, and it is identical to the SEC 14 gene product which is part of the protein secretory machinery and acts in the Golgi complex.