A Kinesin-Related Protein, KRP180, Positions Prometaphase Spindle Poles during Early Sea Urchin Embryonic Cell Division

We have investigated the intracellular roles of an Xklp2-related kinesin motor, KRP180, in positioning spindle poles during early sea urchin embryonic cell division using quantitative, real-time analysis. Immunolocalization reveals that KRP180concentrates on microtubules in the central spindle, but is absent from centrosomes. Microinjection of inhibitory antibodies and dominant negative constructs suggest that KRP180is not required for the initial separation of spindle poles, but instead functions to transiently position spindle poles specifically during prometaphase.