May play 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 (By similarity). Belongs to the TRAPP small subunits family. Sedlin subfamily.