Plus end-directed motor protein required for establishing a bipolar spindle (PubMed:15583027). Associates with both interphase and spindle microtubules (PubMed:15583027). May be involved in nuclear divisions taking place during the development of unfertilized eggs (PubMed:15583027). Required in non-mitotic cells for transport of secretory proteins from the Golgi complex to the cell surface (By similarity). Heterotetramer of two heavy and two light chains. Interacts with aurka. Concentrated around the polar ends of both meiotic and mitotic spindles. In unfertilized eggs, shows highest expression in the germinal vesicle and radial yolk-poor channels. Also present in testis. Expressed maternally. Expressed in eggs but not oocytes (at protein level). The RNA is subject to translational control and is only adenylated in eggs. Expression stops soon after fertilization, when the mRNA is deadenylated. Not expressed in adults. Phosphorylation of Thr-937 during mitosis controls the association of this protein with the spindle apparatus. A subset of this protein primarily localized at the spindle pole is phosphorylated by NEK6 during mitosis. Phosphorylated on a serine residue by aurka. Belongs to the TRAFAC class myosin-kinesin ATPase superfamily. Kinesin family. BimC subfamily. Truncated N-terminus.