Monomeric gamma -tubulin nucleates microtubules.
gamma-Tubulin is required for nucleation and polarized organization of microtubules in vivo. The mechanism of microtubule nucleation by gamma-tubulin and the role of associated proteins is not understood. Here we show that in vitro translated monomeric gamma-tubulin nucleates microtubules by lowering the size of the nucleus from seven to three tubulin subunits. In capping the minus end with high affinity (10(10) m(-1)) and a binding stoichiometry of one molecule of gamma-tubulin/microtubule, gamma-tubulin establishes the critical concentration of the plus end in the medium and prevents minus end growth. gamma-Tubulin interacts strongly with beta-tubulin. A structural model accounts for these results.
Leguy
R
R
Dynamique du Cytosquelette, Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, 91198 Gif-sur-Yvette, France.
Melki
R
R
Pantaloni
D
D
Carlier
M F
MF
D019281:Dimerization; D006801:Humans; D008870:Microtubules / Q000737:chemistry* / Q000378:metabolism; D014404:Tubulin / Q000737:chemistry* / Q000378:metabolism
D014404:Tubulin