Rab family GTPase; required for endosome-to-Golgi, intra-Golgi retrograde, and retrograde Golgi-to-ER transport; GTP-bound Ypt6p temporarily localizes to the Golgi, and dissociates from the membrane into its GDP-bound cytosolic form after Gyp6p GAP is recruited by Ypt32p, a late Golgi GTPase; required for anterograde trafficking of Atg9p to the PAS during starvation-induced autophagy under heat stress, and for the CVT pathway; activated by the Ric1-Rgp1 GEF complex; homolog of mammalian Rab6