A G protein-coupled receptor (GPCR) refers to a type of cell membrane receptor that plays a crucial role in transmitting signals from the external environment to the interior of the cell. GPCRs are integral proteins comprised of seven transmembrane helices that traverse the lipid bilayer multiple times. They are primarily involved in various cellular processes including hormone regulation, sensory perception, neurotransmission, and immune responses.
The activation of GPCRs occurs when a ligand, such as a hormone or neurotransmitter, binds to the extracellular region of the receptor. This binding event triggers a conformational change in the receptor, facilitating the interaction with a G protein, which is a membrane-associated protein. The G protein then undergoes its own activation, causing the exchange of guanosine diphosphate (GDP) for guanosine triphosphate (GTP) on the G protein. This G protein activation subsequently leads to the modulation of various intracellular signaling pathways.
The diversity of GPCRs is expansive, with over 800 different receptor types identified in humans. They can be categorized into different subfamilies based on their structural and functional characteristics. Examples of subfamilies include rhodopsin-like (which includes receptors involved in vision, olfaction, and neurotransmission), adhesion-like, and secretin-like receptors.
Due to their fundamental role in multiple cellular processes, GPCRs are an attractive target for drug development. Many drugs on the market today act by modulating GPCR activity, either by enhancing or inhibiting their function. As a result, GPCRs and their associated signaling pathways are extensively studied in the field of pharmacology to uncover novel therapeutic interventions.
