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Las mutaciones que afectan el bloqueo interno de TEA identifican la probable región de formación de poros de un canal
G Yellen1, M E Jurman, T Abramson
1Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Science (New York, N.Y.)
|February 22, 1991
Resumen
Los investigadores identificaron un aminoácido clave en el canal de potasio de Shaker que influye en la unión del tetraetilamonio (TEA). Este hallazgo pone de relieve una región conservada crucial para la formación del poro de conducción iónica.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La neurociencia es la neurociencia.
- La biofísica es la biofísica.
Sus antecedentes:
- Los canales de potasio activados por voltaje forman poros transmembranares para la permeación rápida y selectiva de iones.
- El ion orgánico tetraetilamonio (TEA) es una sonda que se une a la abertura de los poros intracelulares, bloqueando la corriente de potasio.
Objetivo del estudio:
- Para identificar residuos específicos de aminoácidos que afectan la afinidad de unión del tetraetilamonio (TEA) en los canales de potasio.
- Investigar el papel de las regiones conservadas en la estructura y función de los poros de los canales de potasio.
Principales métodos:
- Se empleó mutagénesis dirigida al sitio para alterar residuos específicos de aminoácidos en el canal de potasio de Drosophila Shaker.
- Se utilizaron técnicas electrofisiológicas para evaluar los efectos de las mutaciones en la unión de TEA y la función del canal.
Principales resultados:
- Se identificó un residuo específico de aminoácidos dentro de una región conservada de 18 aminoácidos como crítico para la afinidad intracelular TEA.
- Este residuo se encuentra entre dos sitios cerca de la abertura externa de los poros, lo que sugiere su participación en la formación de poros.
Conclusiones:
- La región conservada identificada está íntimamente involucrada en la formación del poro de conducción iónica de los canales de potasio activados por voltaje.
- Un segmento corto de ocho residuos de aminoácidos parece atravesar una porción significativa de la diferencia de potencial eléctrico transmembrana.
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