G-Protein-Coupled Receptors

Definition

G-protein-coupled receptors (GPCRs) are large protein complexes that respond to signals outside the cell and activate internal signal transduction pathways and cellular responses by interacting with G-proteins inside the cell.

Related terms

Signal transduction pathway: A series of molecular events initiated by a signal interacting with a receptor on a cell surface leading to specific cellular responses.

Second messenger systems: Intracellular signaling molecules released by the cell in response to exposure to extracellular signaling molecules—the first messengers.

Transmembrane receptor proteins: Proteins embedded within, and spanning across, biological membranes which receive signals from outside cells.