THE KINESIN-LIKE PROTEIN KLP61F IS ESSENTIAL FOR MITOSIS IN DROSOPHILA

We report here that disruption of a recently discovered kinesin-like p rotein in Drosophila melanogaster, KLP61F, results in a mitotic mutati on lethal to the organism. We show that in the absence of KLP61F funct ion, spindle poles fail to separate, resulting in the formation of mon opolar mitotic spindles. The resulting phenotype of metaphase arrest w ith polyploid cells is reminiscent of that seen in the fungal bimC and cut7 mutations, where it has also been shown that spindle pole bodies are not segregated. KLP61F is specifically expressed in proliferating tissues during embryonic and larval development, consistent with a pr imary role in cell division. The structural and functional homology of the KLP61F, bimC, cut7, and Eg5 kinesin-like proteins demonstrates th e existence of a conserved family of kinesin-like molecules important for spindle pole separation and mitotic spindle dynamics.