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El rango de acción del mensajero del ion calcio y el inositol 1,4,5-trisfosfato
N L Allbritton1, T Meyer, L Stryer
1Department of Cell Biology, Stanford University, CA 94305.
Science (New York, N.Y.)
|December 11, 1992
Resumen
El inositol 1,4,5-trisfosfato (IP3) actúa como un mensajero global en células menores de 20 micras, mientras que el calcio (Ca2+) funciona en dominios restringidos debido a su amortiguación.
Área de la Ciencia:
- Señalización celular y biología molecular.
- Biofísica de la difusión y las interacciones moleculares.
Sus antecedentes:
- Los iones de calcio (Ca2+) y el inositol 1,4,5-trisfosfato (IP3) son mensajeros intracelulares críticos.
- Comprender su dinámica de difusión es clave para descifrar las respuestas celulares.
Objetivo del estudio:
- Para determinar el rango efectivo de acción para las fuentes puntuales de Ca2+ e IP3.
- Para comparar las propiedades de difusión de estos mensajeros en un extracto celular.
Principales métodos:
- Medición de los coeficientes de difusión (D) para [3H]IP3 y Ca2+ en el extracto citosólico de ovocitos de Xenopus laevis.
- Análisis de la difusión de Ca2+ en diferentes concentraciones (de 90 nM a 1 microM).
Principales resultados:
- El coeficiente de difusión IP3 (D) fue de 283 micrones^2/s.
- El coeficiente de difusión de Ca2+ (D) osciló entre 13 y 65 micrones2 / s con el aumento de la concentración.
- Los rangos efectivos calculados son: Ca2+ libre (0,1 micras), Ca2+ tamponado (5 micras) y IP3 (24 micras).
Conclusiones:
- IP3 actúa como un mensajero global en células < 20 microns.
- Ca2+ actúa como un mensajero localizado debido al búfer de los componentes móviles e inmóviles.
- El amortiguamiento restringe significativamente el rango de difusión de Ca2+ en comparación con IP3.
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