Central spindle assembly and cytokinesis require a kinesin-like protein/RhoGAP complex with microtubule bundling activity.
A late step in cytokinesis requires the central spindle, which forms during anaphase by the bundling of antiparallel nonkinetochore microtubules. Microtubule bundling and completion of cytokinesis require ZEN-4/CeMKLP-1, a kinesin-like protein, and CYK-4, which contains a RhoGAP domain. We show that CYK-4 and ZEN-4 exist in a complex in vivo that can be reconstituted in vitro. The N terminus of CYK-4 binds the central region of ZEN-4, including the neck linker. Genetic suppression data prove the functional significance of this interaction. An analogous complex, containing equimolar amounts of a CYK-4 ortholog and MKLP-1, was purified from mammalian cells. Biochemical studies indicate that this complex, named centralspindlin, is a heterotetramer. Centralspindlin, but not its individual components, strongly promotes microtubule bundling in vitro.
Mishima
Masanori
M
Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, A-1030, Vienna, Austria.
Kaitna
Susanne
S
Glotzer
Michael
M
D000595:Amino Acid Sequence; D000705:Anaphase / Q000502:physiology; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins; D002455:Cell Division / Q000502:physiology*; D020690:GTPase-Activating Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D016547:Kinesins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D008941:Spindle Apparatus / Q000378:metabolism*
D029742:Caenorhabditis elegans Proteins; D020690:GTPase-Activating Proteins; C114455:ZEN-4 protein, C elegans; C085379:rho GTPase-activating protein; D016547:Kinesins