Plays a role in vesicular transport from endoplasmic reticulum to Golgi. Component of the multisubunit TRAPP (transport protein particle) complex, which includes at least TRAPPC2, TRAPPC2L, TRAPPC3, TRAPPC3L, TRAPPC4, TRAPPC5, TRAPPC8, TRAPPC9, TRAPPC10, TRAPPC11 and TRAPPC12. Interacts with the heterodimer TRAPPC3-TRAPPC6A. Interacts with TRAPPC6A. Expressed in testis, liver, bladder, lung, spleen and brain, several cell lines and primary chondrocytes cell line. The disease may be caused by variants affecting the gene represented in this entry. Belongs to the TRAPP small subunits family. Sedlin subfamily. Intron retention.