Microtubule nucleation by gamma-tubulin-containing rings in the centrosome

Nature. 1995 Dec 7;378(6557):638-40. doi: 10.1038/378638a0.


The microtubule cytoskeleton of animal cells does not assemble spontaneously, but instead requires the centrosome. This organelle consists of a pair of centrioles surrounded by a complex collection of proteins known as the pericentriolar material (PCM). The PCM is required for microtubule nucleation. The minus, or slow-growing, ends of microtubules are embedded in the PCM and the plus, or fast-growing, ends project outwards into the cytoplasm during interphase, or into the spindle apparatus during mitosis. gamma-Tubulin is the only component of the PCM that is so far implicated in microtubule nucleation. Here we use immuno-electron microscopic tomography to show that gamma-tubulin is localized in ring structures in the PCM of purified centrosomes without microtubules. When these centrosomes are used to nucleate microtubule growth, gamma-tubulin is localized at the minus ends of the microtubules. We conclude that microtubule-nucleating sites within the PCM are ring-shaped templates that contain multiple copies of gamma-tubulin.

Publication types

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

MeSH terms

  • Animals
  • Centrosome / chemistry
  • Centrosome / physiology
  • Centrosome / ultrastructure*
  • Drosophila
  • Immunohistochemistry
  • Microscopy, Immunoelectron
  • Microtubules / chemistry
  • Microtubules / metabolism*
  • Microtubules / ultrastructure
  • Tubulin / analysis*
  • Tubulin / physiology*


  • Tubulin