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Las cadenas de luz de miosina del músculo esquelético son esenciales para las velocidades fisiológicas de
S Lowey1, G S Waller, K M Trybus
1Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02254-9110.
Nature
|September 30, 1993
Resumen
Las cadenas de luz de miosina no son esenciales para la actividad enzimática muscular, pero son cruciales para el movimiento. La eliminación de estas cadenas de luz reduce significativamente la velocidad del filamento de actina, lo que afecta la función muscular.
Área de la Ciencia:
- Fisiología muscular La fisiología muscular.
- La función motora molecular tiene su función.
- Bioquímica del músculo esquelético La bioquímica del músculo esquelético.
Sus antecedentes:
- Las cabezas de miosina en el músculo esquelético contienen cadenas ligeras reguladoras (LC2) y cadenas ligeras alcalinas.
- Los roles específicos de estas cadenas de luz de miosina en la función del músculo esquelético de los vertebrados han sido en gran medida desconocidos.
Objetivo del estudio:
- Para investigar la necesidad de las cadenas de luz de miosina para el movimiento muscular.
- Aclarar el papel de las cadenas ligeras en la conversión de la energía química en trabajo mecánico en el músculo.
Principales métodos:
- Preparación de cadenas pesadas de miosina desprovistas tanto de cadena ligera reguladora (LC2) como de cadena ligera alcalina.
- Utilizando un ensayo de motilidad para medir la velocidad del filamento de actina en presencia y ausencia de cadenas de luz.
- Experimentos de reconstitución con cadenas de luz individuales y combinadas para evaluar su impacto en la función de la miosina.
Principales resultados:
- La eliminación de las cadenas de luz de la miosina redujo drásticamente la velocidad de deslizamiento del filamento de actina de 8.8 a 0.8 micras/s.
- La actividad de la ATPasa no se vio afectada en gran medida por la ausencia de cadenas ligeras.
- La reintroducción de cadenas ligeras LC2 o alcalinas restauró parcialmente la velocidad, mientras que la reintroducción de ambas lo restauró por completo.
Conclusiones:
- Las cadenas ligeras de miosina no son esenciales para la actividad enzimática (ATPasa) de la miosina.
- Las interacciones de cadena ligera/cadena pesada son críticas para la eficiente transducción de energía y el movimiento mecánico en el músculo.
- Estos hallazgos ponen de relieve el papel regulador de las cadenas ligeras en la función contráctil muscular.
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