Stimulates specifically the GTPase activity of SEC4, YPT6 and YPT36. Inactivates YPT6 during recycling between the endosome and the Golgi compartments. Interacts with MAC1. Distributed throughout the cytoplasm and accumulates in punctate structures, which concentrate in an actin-dependent manner at sites of polarized growth. Present with 768 molecules/cell in log phase SD medium.