Protein recycling is an important cellular process required for cell homeostasis. Results from prior studies demonstrated that Vps1, a dynamin homologue in yeast, is implicated in protein recycling from the endosome to the trans-Golgi Network (TGN). However, the function of Vps1 in relation to Ypt6, a master GTPase in the recycling pathway, remains unknown. The present study reveals that Vps1 physically interacts with Ypt6 if at least one of them is full-length. It was found that overexpression of full-length Vps1, but not GTP hydrolysis-defective Vps1 mutants, is sufficient to rescue abnormal phenotypes in membrane trafficking pathways provoked by loss of Ypt6 or Vps1. This suggests an essential role of GTP binding and hydrolysis for Vps1 function in the traffic pathway. A series of data from our functional analyses suggest that Ypt6 and Vps1 function parallely for endosome-to-TGN trafficking. Additionally, I identified two novel Vps1 binding partners, Vti1 and Snc2, which function for the endosome-derived vesicle fusion at the TGN, suggesting that Vps1 plays a novel role in later stages of the endosome-to-TGN traffic
