Probing the transducin nucleotide binding site with GDP analogues.

Abstract An affinity study between the G protein of the visual photoreceptor, transducin, and eight different non-hydrolyzable GDP analogues is described. Imidodiphosphate derivatives have been shown to exhibit good affinities to transducin. This very important heterotrimeric G protein is shown to be highly restrictive with regard to structural modifications of the nucleotide at the pyrophosphate moiety, at the 3′ position on ribose, as well as at the N 1 position of the purine.