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 a subunit and dissociation of the a subunit from the bg heterodimer. Depending on its isoform, the GTP-a subunit complex mediates intracellular signaling either indirectly by acting on effector molecules such as adenylyl cyclase (AC) or phospholipase C (PLC), or directly by regulating ion channel or kinase function.

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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).