The proposed studies focus on one of the yeast vacuolar protein sorting (VPS) genes, VPS15. The predicted product of the VPS15 gene shares significant sequence similarity with the catalytic domains of the family of serine/threonine protein kinases. Using both genetic and biochemical approaches, the following will be analyzed: (1) the functional role of myristoylation on Vps15p function and localization, (2) the subcellular location and possible site of action of the Vps15 protein, and (3) the presumed kinase activity of the VPS15 gene product. It is anticipated that these studies will result in a detailed view of the organization and control of vesicular traffic between the Golgi and the vacuole, and possibly other inter-organelle transport events in eukaryotic cells. The process of selective recognition, sorting and transport of proteins from one intracellular organelle to another via vesicular carriers represents an essential feature of all eukaryotic cells. The precise mechanisms and machinery that direct these processes are not yet known. This laboratory has isolated a large collection of yeast mutants that exhibit severe defects in protein delivery to the lysosome-like vacuole. The defective genes in these mutants are likely to encode components of the cell's protein sorting apparatus. Toward an understanding of the molecular and biochemical basis of the vacuolar protein sorting ("vps") defects in these mutants, this research will characterize the roles certain of the VPS genes and their products play in the sorting and delivery of vacuolar enzymes from the Golgi complex to the vacuole in yeast. The fundamental similarities between yeast and other eukaryotic cells in their pathways for protein delivery, together with the powerful genetics and molecular approaches available in yeast, make yeast an ideal organism for addressing these problems.
