Interaction of the Saccharomyces cerevisiae cortical actin patch protein Rvs167p with proteins involved in ER to Golgi vesicle trafficking

We have used affinity chromatography to identify two proteins that bind to the SH3 domain of the actin cytoskeleton protein Rvs167p: Gyp5p and Gy11p. Gyp5p has been shown to be a GTPase activating protein (GAP) for Ypt1p, a Rab GTPase involved in ER to Golgi trafficking; Gy11p is a protein that resembles Gyp5p and has recently been shown to colocalize with and belong to the same protein complex as Gyp5p. We show that Gy11p and Gyp5p interact directly with each other, likely through their carboxyterminal coiled-coil regions. In assays of GAP activity, Gyp5p had GAP activity toward Ypt1p and we found that this activity was stimulated by the addition of Gy11p. Gy11p had no GAP activity toward Ypt1p. Genetic experiments suggest a role for Gyp5p and Gy11p in ER to Golgi trafficking, consistent with their biochemical role. Since Rvs167p has a previously characterized role in endocytosis and we have shown here that it interacts with proteins involved in Golgi vesicle trafficking, we suggest that Rvs167p may have a general role in vesicle trafficking.