Microtubule-based anterograde translocator for membranous organelles. Plus end-directed microtubule sliding activity in vitro. Plays a role in primary cilia formation. Plays a role in centriole cohesion and subdistal appendage organization and function. Regulates the formation of the subdistal appendage via recruitment of DCTN1 to the centriole. Also required for ciliary basal feet formation and microtubule anchoring to mother centriole. Heterodimer of KIF3A and KIF3B (By similarity). Interacts with PIFO (PubMed:20643351). Interacts with CLN3 (PubMed:22261744). Interacts with DCTN1 (By similarity). Interacts with FLCN (PubMed:27072130). Interacts with AP3B1 (PubMed:19934039). Localizes to the subdistal appendage region of the centriole. Belongs to the TRAFAC class myosin-kinesin ATPase superfamily. Kinesin family. Kinesin II subfamily. Extended N-terminus.