Immunostructural evidence for the template mechanism of microtubule nucleation

Nat Cell Biol. 2000 Jun;2(6):352-7. doi: 10.1038/35014045.

Abstract

Two opposing models have been proposed to explain how the gamma-tubulin ring complex (gammaTuRC) induces microtubule nucleation. In the 'protofilament' model, the gammaTuRC induces nucleation as a partially or completely straightened protofilament that is incorporated longitudinally into the wall of the nascent microtubule, whereas the 'template' model proposes that the gammaTuRC acts as a helical template that constitutes the base of the newly-formed polymer. Here we appraise these two models, using high-resolution structural and immunolocalization methods. We show that components of the gammaTuRC localize to a narrow zone at the extreme minus end of the microtubule and that these ends terminate in a pointed cap. Together, these results strongly favour the template model of microtubule nucleation.

Publication types

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

MeSH terms

  • Animals
  • Antibodies / immunology
  • Biopolymers / chemistry
  • Biopolymers / immunology
  • Biopolymers / metabolism
  • Centrifugation
  • Gold
  • Kinesin / genetics
  • Kinesin / metabolism
  • Microscopy, Immunoelectron
  • Microtubules / chemistry
  • Microtubules / immunology
  • Microtubules / metabolism*
  • Microtubules / ultrastructure*
  • Models, Biological*
  • Platinum
  • Protein Structure, Quaternary
  • Replica Techniques
  • Tubulin / chemistry
  • Tubulin / immunology
  • Tubulin / metabolism*
  • Tubulin / ultrastructure*
  • Xenopus laevis

Substances

  • Antibodies
  • Biopolymers
  • Tubulin
  • Platinum
  • Gold
  • Kinesin