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Translocación in vitro de proteínas a través del retículo endoplasmático de la levadura: traslocación

W Hansen, P D Garcia, P Walter

|May 9, 1986

Resumen

La translocación del factor pre-pro-alfa de la levadura en los microsomas ocurre post-traduccionalmente. Este proceso requiere ATP y proteínas específicas, lo que lo diferencia de los sistemas de mamíferos.

Área de la Ciencia:

Biología Molecular Biología Molecular
Biología celular Biología celular.
La bioquímica es la bioquímica.

Sus antecedentes:

La translocación de proteínas a través de las membranas es crucial para la función celular.
Comprender la orientación de las proteínas de la levadura proporciona información sobre los sistemas eucariotas.
El precursor de feromonas del factor alfa (preprofactor alfa) es un modelo para el estudio del transporte de proteínas.

Objetivo del estudio:

Para investigar el mecanismo de translocación del factor pre-pro-alfa a través de las membranas microsomales de la levadura.
Para comparar la translocación de proteínas de levadura con los sistemas de mamíferos.
Identificar los factores y condiciones requeridos para la translocación del factor pre-pro-alfa de la levadura.

Principales métodos:

Síntesis in vitro del factor prepro-alfa.
Ensayos de translocación utilizando sistemas homólogos libres de células germinales de levadura o de trigo con membranas microsomales de levadura.
Análisis de la proteína translocada por glicosilación, protección de la proteasa y extracción de carbonato alcalino.

Principales resultados:

El factor pre-pro-alfa translocado fue glicosilado y protegido de la proteasa, lo que indica un secuestro dentro de las vesículas.
La proteína era soluble después del tratamiento con carbonato alcalino, lo que sugiere que no se integró en la bicapa lipídica.
La translocación del factor pre-pro-alfa de la levadura se produjo post-traduccionalmente, a diferencia de los sistemas de los mamíferos.
El proceso era dependiente del ATP y requería componentes de proteínas térmicamente sensibles en los microsomas de la levadura.

Conclusiones:

El factor pre-pro-alfa se secuestra adecuadamente dentro de las vesículas microsomales de la levadura, pero no se integra en la membrana.
Las membranas microsomales de la levadura facilitan la translocación de proteínas posttranslacionales, un mecanismo distinto de los sistemas de los mamíferos.
El ATP y los factores proteicos específicos son esenciales para esta vía de translocación específica de la levadura.

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