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

Nat Cell Biol. 2000 Jun;2(6):358-64. doi: 10.1038/35014051.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Biopolymers / chemistry
  • Biopolymers / metabolism
  • Biotin / metabolism
  • Centrosome / chemistry
  • Centrosome / metabolism
  • Fluoresceins / metabolism
  • Fluorescent Dyes / metabolism
  • Gold
  • Microscopy, Electron
  • Microtubules / chemistry
  • Microtubules / metabolism*
  • Microtubules / ultrastructure
  • Models, Biological
  • Protein Binding
  • Protein Structure, Quaternary
  • Tubulin / chemistry
  • Tubulin / metabolism*
  • Tubulin / ultrastructure
  • Xenopus laevis

Substances

  • Biopolymers
  • Fluoresceins
  • Fluorescent Dyes
  • Tubulin
  • Biotin
  • Gold