Trs33 (corresponding to human homologues TRAPPC6A and TRAPPC6B) is a subunit of the trafficking protein particle complex (TRAPP). Transport protein particle (TRAPP) complexes are multimeric guanine nucleotide-exchange factors for the GTPase Ypt1. Trs33 is one of the 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 yeast, it is a core component of TRAPP complexes I, II and IV. Complex IV is thought to be involved in autophagy []. In mammals, mutations in TRAPPC6a cause mosaic loss of coat pigment [].
