these results indicate that substitution of the aspartic acid with asparagine at residue 130 of the human beta ar dissociates the well-characterized guanine nucleotide effects on agonist affinity from those on activation of the stimulatory guanine nucleotide-binding regulatory protein and adenylate cyclase and suggests the existence of two distinct counterions for the amine portion of catecholamines that are associated with high- and low-affinity agonist binding states of beta ar .
C0086418
human
C0001643
beta ar