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cdc25 es una tirosina fosfatasa específica que activa directamente el p34cdc2
J Gautier1, M J Solomon, R N Booher
1Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448.
Cell
|October 4, 1991
Resumen
La proteína fosfatasa CDC25 específicamente desfosforila p34cdc2 en la tirosina, activando el complejo ciclina-p34cdc2 e iniciando la fase M en los ovocitos de Xenopus.
Área de la Ciencia:
- Biología celular Biología celular.
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
Sus antecedentes:
- El ciclo celular está regulado por las proteínas cinasas y las fosfatasas.
- CDC25 es un regulador clave del ciclo celular, controlando la actividad del complejo ciclina-p34cdc2.
- Se ha investigado el mecanismo preciso de la actividad de la fosfatasa y la especificidad del sustrato de CDC25.
Objetivo del estudio:
- Para investigar la actividad enzimática y la especificidad del sustrato de la proteína CDC25.
- Para determinar si el CDC25 desfosforila directamente el p34cdc2 y regula la entrada en la fase M.
- Para caracterizar el papel de CDC25 en el control del estado de fosforilación de p34cdc2.2.
Principales métodos:
- Expresión de Drosophila CDC25 en sistemas bacterianos y de levaduras.
- En ensayos in vitro de fosfatasa se utilizan las bacterias expresadas p34cdc2.2.
- Análisis de la inducción de la fase M en ovocitos de Xenopus y extractos de huevo.
- Mutagénesis dirigida al sitio del supuesto sitio catalítico de CDC25.
Principales resultados:
- Drosophila CDC25 activa la ciclina-p34cdc2 inactiva e induce la fase M en los ovocitos de Xenopus.
- CDC25 exhibe homología de secuencia a las proteínas tirosina fosfatasas.
- CDC25 expresado bacterialmente desfosforila específicamente p34cdc2 en el Tyr-15 in vitro.
- Las mutaciones en el sitio catalítico eliminan la actividad tanto in vitro como in vivo CDC25.
- CDC25 demuestra una alta especificidad para p34cdc2, con una desfosforilación mínima de otras proteínas fosforiladas por tirosina.
Conclusiones:
- CDC25 es una proteína específica tirosina fosfatasa que desfosforila directamente el p34cdc2 en el Tyr-15.
- Este evento de desfosforilación es crítico para la activación del complejo ciclina-p34cdc2 y el inicio de la fase M.
- CDC25 juega un papel crucial en la regulación de la activación del MPF (factor promotor de la maduración) a través de la desfosforilación específica de p34cdc2.2.
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