Changes in Apparent Functions of Component Proteins of Adenylate Cyclase System in Rat Brain by Drugs Acting on the Central Nervous System

Transmembrane signalling function of adenylate cyclase system in the cell membranes is discharged and regulated by interactions of the component proteins; receptor protein (either stimulatory (Rs) or inhibitory (Ri)), guanine nucleotide-binding regulatory trimeric protein (either stimulatory (Gs) or inhibitory (Gi)), and catalytic protein (C) for cyclic AMP production (1,2). GTP and its analogs such as guanosine 5′-(β,γ-imino)triphosphate (GppNHp) and guanosine 5′-(γ-thio)triphosphate, regulate the function of G proteins in the presence of Mg2+ (3,4), while F- does in the presence of Al3+ (5). On the other hand, divalent cations, such as Mg2+ and Mn2+, and forskolin directly activate C (6,7). It is also known that cholera and pertussis toxins affect the functions of Gs and Gi, respectively, through ADP-ribosylation of their α-subunits (8, 9).