Does the ternary complex act as a secondary proton pump and a GTP synthase?
It has been suggested that G protein-coupled receptors can act as proton transporters, with the activated G protein-coupled receptor transporting H+ across the membrane from the extracellular side to the cytoplasm. In this article, Paul Nederkoorn, Henk Timmerman and Gabriëlle Donné-Op den Kelder summarize the various H+ translocation mechanisms and how these compare with activated G protein-coupled receptors. The G protein, being part of the ternary complex, is proposed to use translocated protons to synthesize GTP from GDP and Pi, thus functioning in a similar manner to ATP synthase. The importance of these events in physiological effects such as signal amplification is discussed.
Nederkoorn
P H
PH
Department of Pharmacochemistry, Faculty of Chemistry, Vrije Universiteit, Amsterdam, The Netherlands.
Timmerman
H
H
Donné-Op den Kelder
G M
GM
D019204:GTP-Binding Proteins / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000096:biosynthesis; D006868:Hydrolysis; D008025:Ligases / Q000378:metabolism*; D017494:Proton Pumps / Q000502:physiology*; D015398:Signal Transduction
D017494:Proton Pumps; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D008025:Ligases