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Separar los dominios de unión al GTP y los de activación de la GTPasa de una subunidad G alfa
D W Markby1, R Onrust, H R Bourne
1Department of Pharmcology, University of California, San Francisco 94143.
Science (New York, N.Y.)
|December 17, 1993
Resumen
La mayoría de los miembros de la superfamilia de la guanosina trifosfatasa (GTPasa) necesitan una proteína activadora de la GTPasa (GAP) para hidrolizar el trifosfato de guanosina (GTP). Este estudio muestra que una subunidad alfa de la proteína G actúa como un GAP, lo que sugiere un mecanismo general para la regulación de la GTPasa.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- La señalización celular de las células.
Sus antecedentes:
- La superfamilia de la guanosina trifosfatasa (GTPasa) regula los procesos celulares a través de la hidrólisis del trifosfato de guanosina (GTP).
- La mayoría de las GTPasas requieren proteínas activadoras de la GTPasa (GAPs) para hidrolizar eficientemente el GTP.
- Las subunidades alfa de la proteína G heterotrimérica (G alfa) exhiben una hidrólisis rápida de GTP, que difiere de otras GTPasas.
Objetivo del estudio:
- Para investigar la función bioquímica del dominio de inserción único que se encuentra en las subunidades G alfa.
- Para determinar si el dominio de inserción G alfa actúa como una proteína activadora de la GTPasa (GAP).
- Para dilucidar el mecanismo de la hidrólisis rápida de GTP por las subunidades G alfa.
Principales métodos:
- Expresión y purificación del dominio recombinante del inserto G alfa y del dominio del núcleo G alfa que se une al GTP.
- Análisis bioquímicos para medir las tasas de hidrólisis de GTP.
- Análisis de las interacciones proteína-proteína entre los dominios G alfa.
Principales resultados:
- Se demostró que el dominio de inserción G alfa interactúa con el dominio central de unión de G alpha GTP.
- El dominio de inserción G alfa funciona bioquímicamente como una proteína activadora de la GTPasa (GAP).
- Esta interacción acelera significativamente la hidrólisis de GTP por el dominio del núcleo G alfa.
Conclusiones:
- El dominio de inserción de las subunidades G alfa actúa como un GAP intrínseco, explicando su rápida actividad de la GTPasa.
- Se propone un mecanismo general para la hidrólisis de GTP dependiente de GAP, aplicable a otras GTPasas.
- Este hallazgo proporciona información sobre la regulación de las vías de señalización de la proteína G.
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