LAUSR

Yeast dynamin, Vacuolar Protein Sorting 1 (Vps1), has been implicated in recycling traffic from the endosome to the trans-Golgi network (TGN). Previous research showed a genetic interaction of Vps1 with all components of the GARP tethering complex, which anchors vesicles at the late Golgi membrane. We used the yeast two-hybrid system and have identified a 33 amino acid segment of Vps51, a GARP subunit, that interacts with Vps1. Based on sequence homology between Vps51 and its mammalian homolog Ang2 in the 33 amino acids stretch, we identified two key residues of Vps51, E127 and Y129, that bind Vps1. The replacement of these residues led to severe defects in endosome-to-TGN transport of Snc1, providing evidence of the physiological relevance of the interaction of Vps51 with Vps1 for the traffic. Furthermore, our functional analysis revealed that Vps1 acts upstream of Vps51 and that the absence of Vps1 resulted in reduced localization levels of Vps51 and its binding partner Tlg1 to the late Golgi. Taken together, we propose that Vps1 functions with the GARP tethering machinery for efficient tethering/fusion at the TGN.