Enhanced GTPase activity of transducin when bound to cGMP phosphodiesterase in bovine retinal rods.
The generation of the physiological response of a retinal rod cell to an incident photon involves activation of a cGMP phosphodiesterase (PDE) by a GTP-binding protein, transducin (T). This activation has been shown to occur by formation of a membrane-bound T alpha GTP-PDE complex (Clerc, A., and Bennett, N. (1992) J. Biol. Chem. 267, 6620-6627; Catty, P., Pfister, C., Bruckert, F., and Deterre, P. (1992) J. Biol. Chem 267, 19489-19493). The recovery of the response involves turning-off of T by its intrinsic GTPase activity. We show here that the formation of the membrane-bound T alpha GTP-PDE complex correlates with an enhanced rate of GTP hydrolysis. In vivo, this would provide an appropriate mechanism for fast turn-off of cGMP hydrolysis.
Pagès
F
F
Département de Biologie Moléculaire et Structurale, Centre d'Etudes Nucléaires de Grenoble, France.
Deterre
P
P
Pfister
C
C
D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D004789:Enzyme Activation; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D007425:Intracellular Membranes / Q000201:enzymology; D007700:Kinetics; D046911:Macromolecular Substances; D010786:Photoreceptor Cells / Q000201:enzymology*; D015293:Transducin / Q000378:metabolism*
D046911:Macromolecular Substances; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D020558:GTP Phosphohydrolases; D015293:Transducin