Functional heterogeneity of beta gamma-subunit of frog transducin

1. Transducin subunits (T alpha and T beta gamma) were purified from freshly dissected frog (Rana catesbeiana) retinas. It was found that purified T beta gamma is composed of three components which can be separated from each other by an anion exchange column chromatography under nondenaturing conditions. 2. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses of these three components demonstrated that each contains T beta (mol. wt 35,000) and T gamma (mol. wt approximately 8000). 3. Only one of the three components retained an ability to enhance the binding of GppNHp to T alpha in the presence of a photobleaching intermediate of rhodopsin, while the others showed very low abilities to enhance the binding. 4. These observations, together with the similar findings on bovine T beta gamma, strongly suggest that the functional heterogeneity of T beta gamma is conserved in vertebrate photoreceptor cells.