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

[摘要]

A 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.

[学科分类] 生物化学/生物物理

[关键词] Rod outer segment;Light scattering;G-protein;Phosphodiesterase;GTP-γ-S;guanosine;5′-O-(3-thiotriphosphate);ROS;rod outer segments;G-protein;GTP-binding protein or transducin;PDE;cyclic nucleotide phosphodiesterase;Gα-GTP-γ-S;GTP-γ-S bound to the α-subunit of G-protein;DTT;dithiothreitol;NMG;N-methylglucamine;BAPTA;1;2-bis(o-aminophenoxy)-ethane-N;N;N ′;N′-tetraacetic acid