THE SACCHAROMYCES-CEREVISIAE MVP1 GENE INTERACTS WITH VPS1 AND IS REQUIRED FOR VACUOLAR PROTEIN SORTING

The VPS1 gene of Saccharomyces cerevisiae encodes an 80-kDa GTPase tha t associates with Golgi membranes and is required for the sorting of p roteins to the yeast vacuole. Vps1p is a member of a growing family of high-molecular-weight GTPases that are found in a number of organisms and are involved in a variety of cellular processes. Vps1p is most si milar to mammalian dynamin and the Drosophila Shibire protein, both of which have been shown to play a role in an early step of endocytosis. To identify proteins that interact with Vps1p, a genetic screen was d esigned to isolate multicopy suppressors of dominant-negative vps1 mut ations. One such suppressor, MVP1, that exhibits genetic interaction w ith VPS1 and is itself required for vacuolar protein sorting has been isolated. Overproduction of Mvp1p will suppress several dominant allel es of VPS1, and suppression is dependent on the presence of wild-type Vps1p. MVP1 encodes a 59-kDa hydrophilic protein, Mvp1p, which appears to colocalize with Vps1p in vps1(d) and vps27 Delta yeast cells. We t herefore propose that Mvp1p and Vps1p act in concert to promote membra ne traffic to the vacuole.