Microtubule-associated force-producing protein that plays a role in organelle transport. Its motor activity is directed toward the microtubule's plus end. Transports cytoplasmic vesicles and particularly phosphatidylinositol 4,5-bisphosphate-containing liposomes along microtubules. Homodimer. The PH domain is required for kif1-mediated transport probably through its binding and docking onto membrane of cargo vesicles. Belongs to the TRAFAC class myosin-kinesin ATPase superfamily. Kinesin family. Unc-104 subfamily.