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El transportador de glucosa humano puede insertarse posttraducionalmente en los microsomas

M Mueckler, H F Lodish

|February 28, 1986

Resumen

Este estudio revela cómo las proteínas transportadoras de glucosa (GT) se insertan en las membranas. La partícula de reconocimiento de señales (SRP) es crucial para la orientación e inserción de GT, proponiendo un nuevo modelo para la biosíntesis de proteínas.

Área de la Ciencia:

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

Sus antecedentes:

Comprender la inserción de proteínas en las membranas celulares es fundamental para la biología celular.
El transportador de glucosa (GT) es una proteína clave involucrada en la absorción celular de glucosa.
Los modelos anteriores a menudo asumían una estrecha interacción ribosoma-membrana para la inserción de proteínas.

Objetivo del estudio:

Para investigar el mecanismo de la inserción del transportador de glucosa humana (GT) en los microsomas pancreáticos.
Identificar el papel de las secuencias de señales y la vía de la partícula de reconocimiento de señal (SRP) en la biosíntesis de GT.
Proponer un nuevo modelo para la inserción en la membrana de GT y proteínas relacionadas.

Principales métodos:

Síntesis in vitro de transcripciones de ARN para GT humano completo y sus fragmentos (GT-N, GT-C).
Síntesis libre de células de polipéptidos utilizando sistemas de reticulocitos o de germen de trigo.
Evaluación de la inserción en la membrana utilizando endoglucosidasa H, digestión de tripsina y extracción alcalina.

Principales resultados:

Tanto el GT de longitud completa como el fragmento N-terminal (GT-N) pueden insertarse posttraducionalmente en los microsomas.
GT contiene al menos dos secuencias de señales distintas.
La inserción co- y post-traducional de GT-N depende de la partícula de reconocimiento de señal (SRP) y del receptor SRP.
SRP es esencial tanto para la orientación como para iniciar la inserción de los polipéptidos GT.

Conclusiones:

La vía de las partículas de reconocimiento de señales (SRP, por sus siglas en inglés) juega un papel crítico en la inserción en la membrana del transportador de glucosa (GT, por sus siglas en inglés).
Se propone un modelo donde la inserción de la membrana GT no requiere una estrecha interacción ribosoma-membrana.
Este hallazgo ofrece nuevos conocimientos sobre la biosíntesis de proteínas transmembrana con topologías complejas.

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