the guanine nucleotides gtp and guanyl-5'-imido-diphosphate [ gpp ( nh ) p ] , as well as divalent cations , modulate the proportion of the sites with high affinity for agonists as evidenced by their ability to shift the agonist competition curves for [ 3h ] ketanserin-labelled s2 receptors .
C0018328
guanine nucleotides
C0018353
gtp