furthermore , binding of [ 125i ] vip to rat lung receptors was inhibited by micromolar concentrations of gtp analogs , guanosine-5'-o- ( 3-thiotriphosphate ) gtp gamma s ) , and guanylylimidodiphosphate , suggesting that vip receptors in rat lung membranes were tightly coupled to the guanine nucleotide regulatory protein ( ns ) .
C0018353
gtp
C0079469
gtp gamma s