An essential role for a phospholipid transfer protein in yeast Golgi function.

TLDR: It is established for the first time an in vivo function for a phospholipid transfer protein, namely a role in the compartment-specific stimulation of protein secretion, in yeast.

Abstract: PROGRESSION of proteins through the secretory pathway of eukaryotic cells involves a continuous rearrangement of macromolecular structures made up of proteins and phospholipids. The protein SEC14p is essential for transport of proteins from the yeast Golgi complex1. Independent characterization of the SEC14 gene2 and the PIT1 gene3, which encodes a phosphatidy-linositol/phosphatidylcholine transfer protein in yeast, indicated that these two genes are identical. Phospholipid transfer proteins are a class of cytosolic proteins that are ubiquitous among eukaryotic cells and are distinguished by their ability to catalyse the exchange of phospholipids between membranesin vitro4. We show here that the SEC14 and PIT1 genes are indeed identical and that the growth phenotype of a sec 14-1ts mutant extends to the inability of its transfer protein to effect phospholipid transfer in vitro4,5. These results therefore establish for the first time an in vivo function for a phospholipid transfer protein, namely a role in the compartment-specific stimulation of protein secretion.