Trimeric G protein, molecular model

Molecular model of G alpha (a trimeric G protein) in complex with RGS4 (regulator of G-protein signalling, PDB code:1agr), ribbon diagram. G alpha is shown in red with the switch regions I and II in green. RGS4 is shown in blue. Alpha- helices are shown as cylinders.The trimeric guanine nucleotide-binding proteins are involved as transducers in various transmembrane signalling systems. The G alpha (s) protein is involved in hormonal regulation of adenylate cyclase: it activates the cyclase in response to beta- adrenergic stimuli, and is regulated by RGS4.