Dolph, P.J., Man-Son-Hing, H., Yarfitz, S., Colley, N.J., Deer, J.R., Spencer, M., Hurley, J.B., Zuker, C.S. (1994). An eye-specific G beta subunit essential for termination of the phototransduction cascade.  Nature 370(6484): 59--61.

FBrf0072976

Research paper

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.