G-protein-coupled receptor

From Citizendium, the Citizens' Compendium

In biology, G-protein-coupled receptors are the "largest family of cell surface receptors involved in signal transduction. They share a common structure and signal through heterotrimeric g-proteins."^[1]

In signal transduction, cell surface receptors such as G-protein-coupled receptors may activate second messenger systems such as adenyl cyclase-cyclic AMP and cyclic GMP which then may activate protein kinases such as G-protein-coupled receptor kinase which then affect downstream targets (see figure).^[2]

Two principal signal transduction pathways involving the G-protein coupled receptors are proposed: they use either the cyclic AMP or the phosphatidylinositol diphosphate-inositol triphosphate second messenger systems.^[3]

Examples of G-protein-coupled receptors include adrenergic receptors, angiotensin receptors, bradykinin receptors, CCR5 receptor (used by HIV to infect cells), opioid receptors, and purinoceptor P2Y₁₂ (causes platelet aggregation).

References

1. ↑ Anonymous, (2009) G-protein-coupled receptor (English). Medical Subject Headings. U.S. National Library of Medicine.
2. ↑ Lodish, Harvey F. (1999). “20.1. Overview of Extracellular Signaling”, Molecular cell biology. New York: Scientific American Books. ISBN 0-7167-3136-3. 
3. ↑ Gilman AG (1987). G proteins: transducers of receptor-generated signals. Annu. Rev. Biochem. 56: 615–49. DOI:10.1146/annurev.bi.56.070187.003151. PMID 3113327.

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