Arabidopsis GCP2 and GCP3 are part of a soluble gamma-tubulin complex and have nuclear envelope targeting domains.
Fiche publication
Date publication
octobre 2007
Auteurs
Membres identifiés du Cancéropôle Est :
Pr SCHMIT Anne-Catherine
Tous les auteurs :
Seltzer V, Janski N, Canaday J, Herzog E, Erhardt M, Evrard JL, Schmit AC
Lien Pubmed
Résumé
In higher plants, microtubules (MTs) are assembled in distinctive arrays in the absence of a defined organizing center. Three MT nucleation sites have been described: the nuclear surface, the cell cortex and cortical MT branch points. The Arabidopsis thaliana (At) genome contains putative orthologues encoding all the components of characterized mammalian nucleation complexes: gamma-tubulin and gamma-tubulin complex proteins GCP2 to GCP6. We have cloned the cDNA encoding AtGCP2, and show that gamma-tubulin, AtGCP2 and AtGCP3 are part of the same tandem affinity-purified complex and are present in a large membrane-associated complex. In addition, small soluble gamma-tubulin complexes of the size expected for a gamma-tubulin core complex are recruited to isolated nuclei. Using immunogold labelling, AtGCP3 is localized to both the nuclear envelope (NE) and the plasma membrane. To identify domains that could play a role in targeting complexes to these nucleation sites, truncated AtGCP2- and AtGCP3-green fluorescent protein fusion proteins were expressed in BY-2 cells. Several domains from AtGCP2 and AtGCP3 are capable of targeting fusions to the NE. We propose that regulated recruitment of soluble gamma-tubulin-containing complexes is responsible for nucleation at dispersed sites in plant cells and contributes to the formation and organization of the various MT arrays.
Référence
Plant J. 2007 Oct;52(2):322-31