DESCRIPTION: The long term goal of this research is to determine the molecular events which underlie the transport of lysosomal proteins to the yeast lysosome-equivalent, the vacuole. This application focuses on a Ras-like GTPase, Vps21p, and a Sec1 homolog, Vps45p, shown to be important in vacuolar protein sorting. Dr. Horazdovsky will define precisely the step at which these proteins act, and begin to look for interacting proteins and their mechanisms of modulation of Vps21p. Other aims include analysis of transport vesicles carrying Golgi derived proteins to the vacuole, and characterization of the proteinase A sorting proteins.