Specific subunit of the TRAPP II complex, a highly conserved vesicle tethering complex that is required for the proper transport of proteins in post-Golgi trafficking pathways to the growing cell plate in mitotic active cells (PubMed:20713617, PubMed:21689172, PubMed:24443495). Required for the polarized and selective transport of PIN2 and probably PIN1 to the plasma membrane (PubMed:21689172, PubMed:24443495). Not required for ER-to-Golgi as well as biosynthetic and endocytic vacuolar transport (PubMed:21689172). Part of the multisubunit TRAPP (transport protein particle) II complex composed of BET3, BET5, TRS20, TRS23, TRS31, TRS33, TRS65, TRS85, TRS120 and TRS130. Expressed in roots, leaves, stems and flowers. Cytokinesis-defective and seedling-lethal phenotype. Belongs to the TRS120 family.