TRS33 (also known as TRAPPC6A) subunit of the trafficking protein particle complex (TRAPP). TRS33 is one of the six core subunits of TRAPP complexes which play a key role in the regulation of ER-to-Golgi and intra-Golgi transport by tethering the vesicle membrane to the target membrane. In mammals, mutations in TRAPPC6a cause mosaic loss of coat pigment.