Irc15 Is a Microtubule-Associated Protein that Regulates Microtubule Dynamics in Saccharomyces cerevisiae

Department of Biochemistry and Molecular Genetics, University of Virginia Medical Center, Charlottesville, VA 22908, USA.
Current biology: CB (Impact Factor: 9.57). 04/2009; 19(6):472-8. DOI: 10.1016/j.cub.2009.01.068
Source: PubMed


Microtubules are polymers composed of alpha-beta tubulin heterodimers that assemble into microtubules. Microtubules are dynamic structures that have periods of both growth and shrinkage by addition and removal of subunits from the polymer. Microtubules stochastically switch between periods of growth and shrinkage, termed dynamic instability. Dynamic instability is coupled to the GTPase activity of the beta-tubulin subunit of the tubulin heterodimer. Microtubule dynamics are regulated by microtubule-associated proteins (MAPs) that interact with microtubules to regulate dynamic instability. MAPs in budding yeast have been identified that bind microtubule ends (Bim1), that stabilize microtubule structures (Stu2), that bundle microtubules by forming cross-bridges (Ase1), and that interact with microtubules at the kinetochore (Cin8, Kar3, Kip3). IRC15 was previously identified in four different genetic screens for mutants affecting chromosome transmission or repair [11-14]. Here we present evidence that Irc15 is a microtubule-associated protein, localizing to microtubules in vivo and binding to purified microtubules in vitro. Irc15 regulates microtubule dynamics in vivo and loss of IRC15 function leads to delayed mitotic progression, resulting from failure to establish tension between sister kinetochores.

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    • "With the advent of large-scale genomic screens applied to spindle morphogenesis (Hwang et al. 2003; Vizeacoumar et al. 2010) and spindle disassembly (Woodruff et al. 2010), it is certain that MAPs will continue to be identified. Of note is Irc15 (Keyes and Burke 2009), which is found to bind microtubules in vitro and localize to spindles in vivo. "
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