Author(s): Dolph PJ, Man-Son-Hing H, Yarfitz S, Colley NJ, Deer JR, Spencer M, Hurley JB, Zuker CS. An eye-specific G beta subunit essential for termination of the phototransduction cascade. Nature. 1994 Jul 7;370(6484):59-61.
Journal: Nature, Volume 370, Issue 6484, Jul 1994
Heterotrimeric G proteins couple various receptors to intracellular effector molecules. Although the role of the G alpha subunit in effector activation, guanine nucleotide exchange and GTP hydrolysis has been well studied, the cellular functions of the G beta subunits are less well understood. G beta gamma dimers bind G alpha subunits and anchor them to the membrane for presentation to the receptor. In specific systems, the G beta subunits have also been implicated in direct coupling to ion channels and to effector molecules. We have isolated Drosophila melanogaster mutants defective in an eye-specific G-protein beta-subunit (G beta e), and show here that the beta-subunit is essential for G-protein-receptor coupling in vivo. Remarkably, G beta mutants are also severely defective in the deactivation of the light response, demonstrating an essential role for the G beta subunit in terminating the active state of this signalling cascade.