RGS-r, a retinal specific RGS protein, binds an intermediate conformation of transducin and enhances recycling.
G proteins regulate intracellular signaling by coupling a cycle of guanine nucleotide binding and hydrolysis to transient changes of cellular functions. The mechanisms that control the recycling of transducin, the "pacesetting" G protein that regulates mammalian phototransduction, are unclear. We show that a novel retinal specific RGS-motif protein specifically binds to an intermediate conformation involved in GTP hydrolysis by transducin and accelerates phosphate release and the recycling of transducin. This specific interaction further rationalizes the kinetics of the phototransduction cascade and provides a general hypothesis to explain the mechanism of interaction of RGS proteins with other G proteins.
Division of Biology, California Institute of Technology, Pasadena 91125, USA.
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Chen
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Wieland
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Simon
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D002417:Cattle; D017931:DNA Primers; D005136:Eye Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009928:Organ Specificity; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D011487:Protein Conformation; D020710:RGS Proteins; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D012160:Retina / Q000378:metabolism*; D012374:Rod Cell Outer Segment / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015293:Transducin / Q000302:isolation & purification / Q000378:metabolism*
D002352:Carrier Proteins; D017931:DNA Primers; D005136:Eye Proteins; D020710:RGS Proteins; C107413:RGS16 protein; D011994:Recombinant Proteins; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D015293:Transducin