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Diversity of G-Protein-Coupled Receptor Signal Transduction Pathways
Receptors coupled to heterotrimeric GTP-binding proteins (G-proteins) are integral transmembrane proteins that transduce extracellular signals to the cell interior. G-protein-coupled receptors exhibit a common structural motif consisting of seven membrane spanning regions. Receptor occupation promotes interaction between the receptor and the G-protein on the interior surface of the membrane. This induces an exchange of GDP for GTP on the G-protein α subunit and dissociation of the α subunit from the β γ heterodimer. Depending on its isoform, the GTP α subunit complex mediates intracellular signaling either indirectly by acting on effector molecules such as adenylate cyclase (AC) or phospholipase C (PLC), or directly by regulating ion channel or kinase function. References: Schoneberg, T., et al., Structural basis of G-protein-coupled receptor function. Mol. Cell. Endocrinol. 151, 181-193 (1999). LeVine, H., 3rd., Structural features of heterotrimeric G-protein-coupled receptors and their modulatory proteins. Mol. Neurobiol. 19, 111-149 (1999). Morris, A.J., et al., Physiological regulation of G protein-linked signaling. Physiol. Rev. 79, 1373-1430 (1999).
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