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Sigma's Non-specific Protease Activity Assay - Casein as a Substrate
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La actividad endoproteolítica del proteasoma
Chang-Wei Liu1, Michael J Corboy, George N DeMartino
1Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA.
Science (New York, N.Y.)
|December 14, 2002
Resumen
Los proteasomas degradan las proteínas al enhebrarlas a través de un canal. Este estudio revela que los proteasomas pueden degradar las proteínas internamente, incluso sin extremos accesibles, mediante el encierro inducido por el sustrato.
Área de la Ciencia:
- Biología molecular La biología molecular.
- La degradación de las proteínas celulares degradación de las proteínas celulares
- Enzimología Enzimología.
Sus antecedentes:
- El proteosoma es una máquina celular crucial responsable de la degradación de las proteínas reguladoras y mal plegadas.
- Los modelos existentes proponen que los sustratos deben introducir sus terminales a través del canal cerrado del proteasoma para acceder a los sitios catalíticos internos.
Objetivo del estudio:
- Investigar el mecanismo de entrada y degradación del sustrato del proteasoma, en particular para las proteínas nativamente desordenadas.
- Para determinar si los proteasomas pueden degradar sustratos que carecen de terminaciones accesibles.
Principales métodos:
- Se utilizaron sustratos nativos desordenados con y sin terminaciones accesibles.
- Se examinaron los estados latentes (cerrados) y activados (abiertos) del proteasoma.
- Analizaron el sitio de la escisión del enlace peptídico dentro del proteosoma.
Principales resultados:
- Los proteasomas degradan sustratos nativos desordenados en enlaces péptidos internos.
- La degradación se produjo incluso cuando los sustratos carecían de terminales accesibles.
- Los sustratos parecían promover el encierro del proteosoma, facilitando la degradación interna.
Conclusiones:
- Este mecanismo endoproteolítico permite a los proteasomas degradar sustratos internamente, independientemente de los terminales accesibles.
- Este hallazgo proporciona una base molecular para la liberación regulada de factores de transcripción de precursores inactivos.
- También ofrece un mecanismo para acceder y degradar los defectos de plegado interno en proteínas multidominio mal plegadas.
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