Probing the transducin nucleotide binding site with GDP analogues

An affinity study between the G protein of the visual photoreceptor, transd ucin, and eight different non-hydrolyzable GDP analogues is described. Imid odiphosphate derivatives have been shown to exhibit good affinities to tran sducin. This very important heterotrimeric G protein is shown to be highly restrictive;e 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. (C) 2001 Elsevier Science Ltd. All rights reser ved.