An eye-specific G beta subunit essential for termination of the phototransduction cascade.
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.
Howard Hughes Medical Institute, University of California at San Diego, La Jolla 92093-0649.
P J
PJ
Dolph
H
H
Man-Son-Hing
S
S
Yarfitz
N J
NJ
Colley
J R
JR
Deer
M
M
Spencer
J B
JB
Hurley
C S
CS
Zuker
D000818:Animals; D002118:Calcium / Q000378:metabolism; D004331:Drosophila melanogaster; D004594:Electrophysiology; D005123:Eye / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008027:Light; D009154:Mutation; D009431:Neural Conduction; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism*; D012243:Rhodopsin / Q000378:metabolism
D012243:Rhodopsin; D019204:GTP-Binding Proteins; D002118:Calcium