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BP: Fachverband Biologische Physik

BP 8: Active Filament Networks

BP 8.7: Vortrag

Dienstag, 26. Februar 2008, 11:45–12:00, C 243

Microtubule-driven multimerization recruits ase1 onto overlapping microtubules — Lukas C. Kapitein¹, Marcel E. Janson¹, •Christoph F. Schmidt², and Erwin J.G. Peterman¹ — ¹Vrije Universiteit, Amsterdam, The Netherlands — ²Georg-August-Universität, Göttingen, Germany

Microtubule cross-linking proteins of the ase1/PRC1/Map65 family play a major role in the construction of microtubule networks such as the mitotic spindle. Most homologues have been shown to localize with a remarkable specificity to sets of antiparallel overlapping microtubules. Using in vitro experiments in combination with single-molecule fluorescence microscopy, we obtained evidence for a mechanism of localized protein multimerization underpinning this specific targeting. Dimers of the fission yeast homologue, ase1, diffused along the lattice of single microtubules and assembled into stable multimeric structures at concentrations above a threshold. This threshold was significantly lower between overlapping microtubules. These findings show that cells use a finely tuned cooperative localization mechanism that exploits differences in the geometry and concentration of ase1 binding sites along single and overlapping MTs.