A bipolar kinesin.
Kashina, A. S.; Baskin, R. J.; Cole, D. G.; Wedaman, K. P.; Saxton, W. M.; Scholey, J. M.
[Letter] Nature. 379(6562):270-272, January 18, 1996.

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CHROMOSOME segregation during mitosis depends on the action of the mitotic spindle, a self-organizing, bipolar protein machine which uses microtubules (MTs) and their associated motors [1,2]. Members of the BimC subfamily of kinesin-related MT-motor proteins are believed to be essential for the formation and functioning of a normal bipolar spindle [3-14]. Here we report that KRP130, a homotetrameric BimC-related kinesin purified from Drosophila melanogaster embryos [13], has an unusual ultrastructure. It consists of four kinesin-related polypeptides assembled into a bipolar aggregate with motor domains at opposite ends, analogous to a miniature myosin filament [15]. Such a bipolar 'minifilament' could crosslink spindle MTs and slide them relative to one another. We do not know of any other MT motors that have a bipolar structure.

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