Binding of transductin to light-activated rhodopsin prevents transducin interaction with the rod cGMP phosphodiesterase gamma-subunit

The interactions of transducin with the two identical inhibitory subunits of phosphodiesterase (P-gamma) and the influence of rhodopsin on the binding have been studied. Results indicate a 6-fold maximal increase in the probe fluorescence when transducin is added to P-gamma-BC, while the fluorescence was increased by 2.3-fold. The G(sub t-beta-gamma) subunits had no significant effect on the binding of transducin to P-gammaBC or P-gamma-24-45BC.