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Mecanismo estructural de la activación del ligando en el receptor GABA (B) humano

Yong Geng¹, Martin Bush¹, Lidia Mosyak¹

¹Department of Pharmacology, Columbia University, New York, New York 10032, USA.

|December 6, 2013

Resumen

El receptor humano GABA (B), crucial para la inhibición cerebral, fue analizado estructuralmente. Los agonistas lo activan cerrando los dominios GBR1, revelando una nueva interfaz de heterodimero.

Área de la Ciencia:

La neurociencia es la neurociencia.
Biología Estructural Biología estructural.
La bioquímica es la bioquímica.

Sus antecedentes:

El receptor humano GABA (B) es un receptor acoplado a la proteína G esencial para la neurotransmisión inhibidora.
Funciona como un heterodimero obligatorio compuesto de subunidades GBR1 y GBR2.

Objetivo del estudio:

Para aclarar la base estructural de la activación del receptor GABA.
Para caracterizar los cambios conformacionales e interacciones involucradas en la señalización del receptor.

Principales métodos:

Se empleó cristalografía de rayos X para determinar las estructuras de los dominios extracelulares GBR1-GBR2.
Se obtuvieron estructuras para estados apo, agonista y antagonista.

Principales resultados:

Tanto las subunidades GBR1 como GBR2 adoptan una conformación abierta en el estado de reposo (apo y ligado al antagonista).
La unión del agonista induce el cierre del dominio específicamente en la subunidad GBR1, lo que significa el estado activo.
Los agonistas y antagonistas se unen a un sitio superpuesto dentro de la grieta interdominio GBR1.
Durante la activación se forma una nueva interfaz de heterodimero entre GBR1 y GBR2.

Conclusiones:

El receptor GABA exhibe un mecanismo de activación único que implica el cierre del dominio GBR1 tras la unión del agonista.
Las perspectivas estructurales revelan cómo los antagonistas estabilizan el estado inactivo y los agonistas promueven la activación.
La interfaz de heterodimero identificada es crítica para la función del receptor y la señalización.

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