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. {ECO:0000269|PubMed:10545495; ECO:0000269|PubMed:12015984}.