Association of brain gamma-tubulins with alpha beta-tubulin dimers.
gamma-Tubulin is necessary for nucleation and polar orientation of microtubules in vivo. The molecular mechanism of microtubule nucleation by gamma-tubulin and the regulation of this process are not fully understood. Here we show that there are two gamma-tubulin forms in the brain that are present in complexes of various sizes. Large complexes tend to dissociate in the presence of a high salt concentration. Both gamma-tubulins co-polymerized with tubulin dimers, and multiple gamma-tubulin bands were identified in microtubule protein preparations under conditions of non-denaturing electrophoresis. Immunoprecipitation experiments with monoclonal antibodies against gamma-tubulin and alpha-tubulin revealed interactions of both gamma-tubulin forms with tubulin dimers, irrespective of the size of complexes. We suggest that, besides small and large gamma-tubulin complexes, other molecular gamma-tubulin form(s) exist in brain extracts. Two-dimensional electrophoresis revealed multiple charge variants of gamma-tubulin in both brain extracts and microtubule protein preparations. Post-translational modification(s) of gamma-tubulins might therefore have an important role in the regulation of microtubule nucleation in neuronal cells.
Sulimenko
Vadym
V
Institute of Molecular Genetics, Department of Biology of Cytoskeleton, Academy of Sciences of the Czech Republic, 142 20 Prague 4, Czech Republic.
Sulimenko
Tetyana
T
Poznanovic
Slobodan
S
Nechiporuk-Zloy
Volodymyr
V
Böhm
Konrad J
KJ
Macurek
Libor
L
Unger
Eberhard
E
Dráber
Pavel
P
D000818:Animals; D001923:Brain Chemistry; D002458:Cell Fractionation; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D020033:Protein Isoforms; D013552:Swine; D014020:Tissue Extracts / Q000737:chemistry / Q000378:metabolism; D014404:Tubulin / Q000737:chemistry* / Q000378:metabolism*
D020033:Protein Isoforms; D014020:Tissue Extracts; D014404:Tubulin