G-protein-coupled receptor

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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][2]

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).^[3]

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.^[4]

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).

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