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Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells
Published on: October 1, 2010
Características del canal de calcio conferidas al canal de sodio por mutaciones únicas
S H Heinemann1, H Terlau, W Stühmer
1Max-Planck-Institut für biophysikalische Chemie, Abteilung Membranbiophysik, Göttingen, Germany.
Nature
|April 2, 1992
Resumen
Los aminoácidos clave en los canales de sodio controlan a través de cuáles pasan los iones, diferenciándolos de los canales de calcio. Las mutaciones que alteran estos residuos cambian la selectividad iónica, revelando su papel en el canal.
Área de la Ciencia:
- Biología molecular La biología molecular.
- La biofísica es la biofísica.
- La neurociencia es la neurociencia.
Sus antecedentes:
- Los canales de sodio son canales de iones regulados por voltaje que son cruciales para la electrofisiología celular.
- Su alta selectividad para los iones Na+ los distingue de los canales de calcio y potasio.
- Se supone que los residuos específicos de aminoácidos en el poro determinan la selectividad iónica.
Objetivo del estudio:
- Para investigar el papel de los residuos de aminoácidos específicos en la determinación de la selectividad iónica del canal de sodio.
- Comprender cómo las diferencias estructurales en los canales iónicos influyen en la permeación iónica.
- Para identificar los componentes clave del filtro de selectividad del canal de sodio.
Principales métodos:
- Mutagénesis dirigida al sitio del canal II de sodio de la rata.
- Registros electrofisiológicos para evaluar la selectividad y conductancia de iones.
- Comparación de las propiedades del canal de tipo salvaje y mutante.
Principales resultados:
- Las mutaciones de lisina 1,422 (repetición III) y alanina 1,714 (repetición IV) al ácido glutámico alteraron la selectividad iónica.
- Estas sustituciones cambiaron las propiedades de los canales de sodio hacia las de los canales de calcio.
- Los residuos identificados son críticos para distinguir entre Na+ y otros iones.
Conclusiones:
- La lisina 1.422 y la alanina 1.714 son determinantes esenciales de la selectividad iónica del canal de sodio.
- Es probable que estos residuos formen parte del filtro de selectividad del canal.
- Las modificaciones estructurales en estos sitios pueden imitar funcionalmente la selectividad de los canales de calcio.
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