XMAP215 is required for the microtubule-nucleating activity of centrosomes.
Curr Biol
; 12(15): 1326-30, 2002 Aug 06.
Article
em En
| MEDLINE
| ID: mdl-12176362
ABSTRACT
Microtubules are essential structures that organize the cytoplasm and form the mitotic spindle. Their number and orientation depend on the rate of nucleation events and their dynamics. Microtubules are often, but not always, nucleated off a single cytoplasmic element, the centrosome. One microtubule-associated protein, XMAP215, is also a resident centrosomal protein. In this study, we have found that XMAP215 is a key component for the microtubule-nucleating activity of centrosomes. We show that depletion of XMAP215 from Xenopus egg extracts impairs their ability to reconstitute the microtubule nucleation potential of salt-stripped centrosomes. We also show that XMAP215 immobilized on polymer beads induces the formation of microtubule asters in egg extracts as well as in solutions of pure tubulin. Formation of asters by XMAP215 beads indicates that this protein is able to anchor nascent microtubules via their minus ends. The aster-forming activity of XMAP215 does not require gamma-tubulin in pure tubulin solutions, but it is gamma-tubulin-dependent in egg extracts. Our results indicate that XMAP215, a resident centrosomal protein, contributes to the microtubule-nucleating activity of centrosomes, suggesting that, in vivo, the formation of asters by centrosomes requires factors additional to gamma-tubulin.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Oócitos
/
Núcleo Celular
/
Centrossomo
/
Proteínas de Xenopus
/
Proteínas Associadas aos Microtúbulos
/
Microtúbulos
Limite:
Animals
Idioma:
En
Revista:
Curr Biol
Assunto da revista:
BIOLOGIA
Ano de publicação:
2002
Tipo de documento:
Article
País de afiliação:
Alemanha