The Balance Between τ Protein's Microtubule Growth and Nucleation Activities: Implications for the Formation of Axonal Microtubules |
| |
Authors: | Roland Brandt Gloria Lee |
| |
Institution: | Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School Boston, Massachusetts, U.S.A. |
| |
Abstract: | Abstract: The microtubule-associated protein τ is found primarily in neuronal tissues and is highly enriched in the axon. It promotes microtubule assembly in vitro and stabilizes microtubules in cells. To study how τ protein might be involved in the unique features of axonal microtubules, we have analyzed the effect of E. coli -synthesized τ protein using an in vitro centrosome-mediated microtubule regrowth assay over a wide range of τ/tubulin ratios. We report that microtubule assembly promoted by τ protein exhibits characteristic changes dependent on the τ/tubulin ratio. Above a threshold level, nucleation of new microtubules is favored over growth of existing ones, τ isoform variation does not change this phase transition in microtubule assembly. We discuss how τ might participate in the elaboration of axonal morphology based on our results and present evidence that the phase transition from microtubule growth to nucleation is critical for axonal development. |
| |
Keywords: | τ Microtubule-associated proteins Microtubule assembly Axonal development |
|
|