The amplified P-signal, an extremely photosensitive light scattering signal from rod outer segments, which is not affected by pre-activation of phosphodiesterase with Gα-GTP-γ-S

Abstract

AbstractA light scattering signal from bovine rod outer segments in the presence of GTP is described. It has the same angular dependence as the P-signal but is 3 orders of magnitude more sensitive to light and therefore we have called in the amplified P-signal. Adding Gα-GTP-γ-S has no significant effect on the light scattering signal despite the activation of PDE. cGMP affects the amplified P-signal, but subsequent addition of Gα-GTP-γ-S restores the normal signal character. All these facts strongly support the view that the amplified P-signal reflects G-protein activation rather than that of PDE. This is in striking contrast to an interpretation of a very similar light scattering signal previously described by other groups