The bipolar kinesin, KLP61F, cross-links microtubules within interpolar microtubule bundles of Drosophila embryonic mitotic spindles

David J. Sharp, Kent L. McDonald, Heather M. Brown, Heinrich J. Matthies, Claire Walczak, Ron D. Vale, Timothy J. Mitchison, Jonathan M. Scholey

Research output: Contribution to journalArticle

230 Scopus citations

Abstract

Previous genetic and biochemical studies have led to the hypothesis that the essential mitotic bipolar kinesin, KLP61F, cross-links and slides microtubules (MTs) during spindle assembly and function. Here, we have tested this hypothesis by immunofluorescence and immunoelectron microscopy (immunoEM). We show that Drosophila embryonic spindles at metaphase and anaphase contain abundant bundles of MTs running between the spindle poles. These interpolar MT bundles are parallel near the poles and antiparallel in the midzone. We have observed that KLP61F motors, phosphorylated at a cdk1/cyclin B consensus domain within the BimC box (BCB), localize along the length of these interpolar MT bundles, being concentrated in the midzone region. Nonphosphorylated KLP61F motors, in contrast, are excluded from the spindle and display a cytoplasmic localization. Immunoelectron microscopy further suggested that phospho-KLP61F motors form cross-links between MTs within interpolar MT bundles. These bipolar KLP61F MT-MT cross-links should be capable of organizing parallel MTs into bundles within half spindles and sliding antiparallel MTs apart in the spindle midzone. Thus we propose that bipolar kinesin motors and MTs interact by a 'sliding filament mechanism' during the formation and function of the mitotic spindle.

Original languageEnglish (US)
Pages (from-to)125-138
Number of pages14
JournalJournal of Cell Biology
Volume144
Issue number1
DOIs
StatePublished - Jan 11 1999

Keywords

  • Bim C
  • Bipolar kinesin
  • Drosophila
  • Microtubule
  • Mitosis

ASJC Scopus subject areas

  • Cell Biology

Fingerprint Dive into the research topics of 'The bipolar kinesin, KLP61F, cross-links microtubules within interpolar microtubule bundles of Drosophila embryonic mitotic spindles'. Together they form a unique fingerprint.

  • Cite this

    Sharp, D. J., McDonald, K. L., Brown, H. M., Matthies, H. J., Walczak, C., Vale, R. D., Mitchison, T. J., & Scholey, J. M. (1999). The bipolar kinesin, KLP61F, cross-links microtubules within interpolar microtubule bundles of Drosophila embryonic mitotic spindles. Journal of Cell Biology, 144(1), 125-138. https://doi.org/10.1083/jcb.144.1.125