Functions in endoplasmic reticulum to Golgi vesicle-mediated transport and regulates the proper organization of the endoplasmic reticulum and the Golgi (By similarity). Plays a key role in targeting to neuronal dendrites receptors such as HTR1A (PubMed:18685031). Plays also a role in primary cilium and sperm flagellum assembly probably through protein transport to these compartments (By similarity). Interacts with HTR1A (via C-terminus) (PubMed:18685031). Interacts with ABCB9 (via TMD0); this interaction allows (but is not essential) the ER-to-Golgi trafficking and strongly depends on a salt bridge within TMD0 (By similarity). Shuttles between the endoplasmic reticulum, the intermediate compartment and the Golgi apparatus. Highly expressed in brain. Expressed in heart, kidney, and lung and lower levels in spleen, muscle, and intestine (at protein level) (PubMed:18685031). Expressed in serotoninergic neurons (at protein level) (PubMed:18685031). Belongs to the YIF1 family. Truncated N-terminus.