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Participación de las proteínas "G" de unión a GTP en el transporte a través de la pila de Golgi
P Melançon1, B S Glick, V Malhotra
1Department of Biochemistry, Stanford University, California 94305.
Cell
|December 24, 1987
Resumen
Las proteínas de unión de nucleótidos de guanina (proteínas G) regulan el transporte de proteínas de Golgi. GTP gamma S inhibe este transporte al bloquear las membranas del receptor Golgi, afectando un paso clave de la fusión.
Área de la Ciencia:
- Biología celular Biología celular.
- Biología Molecular Biología Molecular
- Mecanismos de transporte de las proteínas.
Sus antecedentes:
- El aparato de Golgi es crucial para modificar y clasificar las proteínas.
- El transporte intracelular de proteínas depende del tráfico de vesículas entre los compartimentos de Golgi.
- Las proteínas de unión de nucleótidos de guanina (proteínas G) son reguladores conocidos de la señalización y el tráfico celular.
Objetivo del estudio:
- Para investigar el papel de las proteínas G en el transporte de proteínas intra-Golgi.
- Para aclarar el mecanismo específico por el cual GTP gamma S afecta a la función de Golgi.
- Para identificar la etapa del transporte mediado por vesículas inhibido por GTP gamma S.
Principales métodos:
- Utilizó un sistema libre de células para estudiar el transporte de proteínas entre los compartimentos de Golgi.
- Empleado GTP gamma S y fluoruro / iones de aluminio para inhibir el transporte.
- Realizó experimentos de preincubación para distinguir las funciones de la membrana del donante y del aceptador.
- Microscopía electrónica aplicada para visualizar las estructuras de Golgi y la dinámica de las vesículas.
Principales resultados:
- GTP gamma S inhibió irreversiblemente el transporte de proteínas entre los compartimentos de Golgi.
- Los iones fluoruro/aluminio imitaron el efecto inhibidor, lo que sugiere la participación de la proteína G.
- La inhibición requería un factor citosólico y afectaba específicamente a las membranas del receptor Golgi.
- Se identificó como el objetivo un paso de procesamiento entre la fijación de la vesícula y la fusión.
- La microscopía electrónica mostró un aumento de 5 veces en los brotes y vesículas no recubiertas de clatrina.
Conclusiones:
- Las proteínas G son esenciales para regular el transporte de proteínas a través de la pila de Golgi.
- GTP gamma S inhibe el transporte de Golgi al interferir con la fusión de las vesículas en las membranas aceptoras.
- Los hallazgos destacan un papel crítico para la señalización de la proteína G en el mantenimiento de la integridad y la función compartimental de Golgi.
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