DSK1, a kinesin-related protein involved in anaphase spindle elongation, is a component of a mitotic spindle matrix

✍ Scribed by Wein, Harrison ;Bass and, Hank W. ;Cande, W. Zacheus

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 216 KB
• Volume: 41
• Category: Article
• ISSN: 0886-1544
• DOI: 10.1002/(sici)1097-0169(1998)41:3<214::aid-cm3>3.0.co;2-p

✦ Synopsis

DSK1 is a kinesin-related protein that is involved in anaphase spindle elongation in the diatom Cylindrotheca fuisiformis [Wein et al., 1996: J. Cell Biol. 113:595-604]. DSK1 staining appeared to be concentrated in the gap that forms as the two half-spindles separate, suggesting that DSK1 may be part of a non-microtubule spindle matrix. We set out to investigate this possibility using three-dimensional high-resolution fluorescence microscopy, and biochemical methods of tubulin extraction. Three-dimensional fluorescence microscopy reveals that DSK1 remains in the midzone after the bulk of the microtubules from the two half-spindles have left the region. Biochemical studies show that CaCl2 extraction of tubulin from a mitotic spindle preparation does not extract similar proportions of DSK1 protein. Immunofluorescence confirms that this CaCl2 extraction leaves behind spindle-like bars that are recognized by anti-DSK1, but not by anti-tubulin antibodies. We conclude that DSK1 is part of, or attached to, a non-microtubule scaffold in the diatom central spindle. This discovery has implications for both the structural organization of the mitotic spindle and the mechanism of spindle elongation.