Gproteiinikytköksiset

Gproteiinikytköksiset, known in English as G protein-coupled receptors (GPCRs), constitute a large family of cell surface receptors that play a crucial role in signal transduction. These receptors are involved in sensing molecules outside the cell and activating internal signal pathways, ultimately leading to a cellular response. When an extracellular signaling molecule, such as a hormone or neurotransmitter, binds to a GPCR, the receptor undergoes a conformational change. This change allows the GPCR to interact with an intracellular G protein. The G protein, typically a trimeric complex composed of alpha, beta, and gamma subunits, then exchanges its bound guanosine diphosphate (GDP) for guanosine triphosphate (GTP). This GTP binding activates the G protein, causing it to dissociate into its alpha subunit and a beta-gamma dimer. Both of these activated components can then go on to modulate the activity of various downstream effector proteins, such as enzymes and ion channels, initiating a cascade of intracellular events. The diverse range of signaling molecules that bind to GPCRs and the variety of cellular processes they regulate highlight their importance in physiology. Consequently, GPCRs are targets for a significant percentage of currently marketed drugs, underscoring their therapeutic relevance.