Microtubule-Driven Multimerization Recruits ase1p onto Overlapping Microtubules

作者：Kapitein Lukas C; Janson Marcel E; van den Wildenberg Siet M J L; Hoogenraad Casper C; Schmidt Christoph F; Peterman Erwin J G^*

来源：Current Biology, 2008, 18(21): 1713-1717.

DOI：10.1016/j.cub.2008.09.046

Microtubule (MT) crosslinking proteins of the ase1p/PRC1/Map65 family play a major role in the construction of MT networks such as the mitotic spindle. Most homologs in this family have been shown to localize with a remarkable specificity to sets of MTs that overlap with an antiparallel relative orientation [1-4]. Regulatory proteins bind to ase1p/PRC1/Map65 and appear to use the localization to set up precise spatial signals [5-10]. Here, we present evidence for a mechanism of localized protein multimerization underlying the specific targeting of ase1p, the fision yeast homolog. In controlled in vitro experiments, dimers of ase1-GFP diffused along the surface of single MTs and, at concentrations above a certain threshold, assembled into static multimeric structures. We observed that this threshold was significantly lower on overlapping MTs. We also observed diffusion and multimerization of ase1-GFP on MTs inside living cells, suggesting that a multimerization-driven localization mechanism is relevant in vivo. The domains responsible for MT binding and multimerization were identified via a series of ase1p truncations. Our findings show that cells use a finely tuned cooperative localization mechanism that exploits differences in the geometry and concentration of ase1p binding sites along single and overlapping MTs.

• 出版日期2008-11-11