Effect of GTP on the rhodopsin-G-protein complex by transient formation of extra metarhodopsin II.
The light-induced transient interaction between rhodopsin and G-protein in the presence of GTP has been measured by the formation of extra metarhodopsin II. Disc membranes were recombined with the hypotonic extract containing the G-protein. Without GTP, a flash induces stable rhodopsin-G-protein complexes which dissociate upon addition of GTP. In low GTP (less than 10 microM) transient rhodopsin X G-protein interaction is observed. Rhodopsin X G-protein dissociates the faster, the more GTP is present (rate of dissociation, 0.3/s at 5 microM GTP; T = 3.5 degrees C). The results corroborate that the uptake of GTP terminates the rhodopsin-G-protein complex and allow an estimation of the rhodopsin X G-protein lifetime.
D000818:Animals; D002417:Cattle; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000494:pharmacology*; D007700:Kinetics; D008027:Light; D012168:Retinal Pigments / Q000378:metabolism*; D012243:Rhodopsin / Q000031:analogs & derivatives / Q000378:metabolism*; D012374:Rod Cell Outer Segment / Q000032:analysis
D012168:Retinal Pigments; C013110:metarhodopsins; D006160:Guanosine Triphosphate; D012243:Rhodopsin; D019204:GTP-Binding Proteins