Specific subunit of the TRAPP II complex, a highly conserved vesicle tethering complex that functions in the late Golgi as a guanine nucleotide exchanger (GEF) for the Golgi YPT1 GTPase. TRS65 plays a role in the YPT GEF activity of TRAPP II in concert with the two other TRAPP II-specific subunits TRS120 and TRS130. Involved in cell wall (1-->6)-beta-glucan synthesis. Glycan metabolism; beta-glucan biosynthesis. Part of the multisubunit TRAPP (transport protein particle) II complex composed of BET3, BET5, TRS20, TRS23, TRS31, TRS33, TRS65, TRS120 and TRS130. Interacts directly with TRS120 and TRS130. Present with 1660 molecules/cell in log phase SD medium.