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- Title
The molecular function of Ase1p: evidence for a MAP-dependent midzone-specific spindle matrix.
- Authors
Schuyler, Scott C.; Liu, Jenny Y.; Pellman, David
- Abstract
The midzone is the domain of the mitotic spindle that maintains spindle bipolarity during anaphase and generates forces required for spindle elongation lanaphase B). Although there is a clear role for microtubule (MT) motor proteins at the spindle midzone, less is known about how microtubule-associated proteins (NAPs) contribute to midzone organization and function. Here, we report that budding yeast Ase1p is a member of a conserved family of midzone-specific MAPs. By size exclusion chromatography and velocity sedimentation both Ase1p in extracts and purified Ase1p behaved as a homodimer. Ase1p bound and bundled MTs in vitro. By live cell microscopy, loss of Ase1p resulted in a specific defect: premature spindle disassembly in mid-anaphase. Furthermore, when overexpressed, Ase1p was sufficient to trigger spindle elongation in S phase-arrested cells. FRAP revealed that Ase1p has both a very slow rate of turnover within the midzone and limited lateral diffusion along spindle MTs. We propose that Ase1p functions as an MT cross-bridge that imparts matrix-like characteristics to the midzone. MT-dependent networks of spindle midzone MAPs may be one molecular basis for the postulated spindle matrix.
- Subjects
PROTEINS; MICROTUBULES; SPINDLE apparatus
- Publication
Journal of Cell Biology, 2003, Vol 160, Issue 4, p517
- ISSN
0021-9525
- Publication type
Article
- DOI
10.1083/jcb.200210021