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Nat Cell Biol. 2000 Jun;2(6):358-64.

A new function for the gamma-tubulin ring complex as a microtubule minus-end cap.

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  • 1Department of Embryology, Carnegie Institution of Washington, 115 West University Parkway, Baltimore, Maryland 21210, USA.


Microtubule nucleation from centrosomes involves a lockwasher-shaped protein complex containing gamma-tubulin, named the gamma-tubulin ring complex (gammaTuRC). Here we investigate the mechanism by which the gammaTuRC nucleates microtubules, using a direct labelling method to visualize the behaviour of individual gammaTuRCs. A fluorescently-labelled version of the gammaTuRC binds to the minus ends of microtubules nucleated in vitro. Both gammaTuRC-mediated nucleation and binding of the gammaTuRC to preformed microtubules block further minus-end growth and prevent microtubule depolymerization. The gammaTuRC therefore acts as a minus-end-capping protein, as confirmed by electron-microscopic examination of gold-labelled gammaTuRCs. These data support a nucleation model for gammaTuRC function that involves capping of microtubules.

[PubMed - indexed for MEDLINE]
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