GPCRsignalointia

GPCRsignalointia refers to the cellular signaling processes initiated by G protein-coupled receptors (GPCRs), a large and diverse family of cell-surface receptors responsive to a broad range of ligands including hormones, neurotransmitters, and sensory stimuli. GPCRs are found across eukaryotes and constitute a major target class for pharmaceutical intervention, with many drugs acting at these receptors.

Receptors share a common architecture of seven transmembrane helices, with extracellular ligand-binding sites and intracellular interfaces for heterotrimeric G proteins. When a ligand binds, GPCRs undergo conformational changes that promote GDP–GTP exchange on the Gα subunit. This activation causes dissociation of Gα-GTP from the Gβγ dimer, enabling downstream signaling through effectors such as adenylyl cyclase (altering cAMP levels), phospholipase Cβ (producing IP3 and DAG and raising intracellular calcium), ion channels, and various kinases. Signaling can proceed via different G protein families, including Gs, Gi/o, Gq/11, and G12/13, producing diverse cellular responses. In addition to G protein–dependent pathways, GPCRs can signal through β-arrestins and other scaffolding proteins, a mode often referred to as biased signaling.

Signaling is tightly regulated. GPCRs can be phosphorylated by GPCR kinases (GRKs) and bound by arrestins, leading to desensitization and often receptor internalization. Receptors may be recycled to the membrane or targeted for degradation. GPCRsignalointia thus encompasses both the canonical G protein pathways and arrestin-mediated routes, contributing to the complexity of physiological regulation.

Physiologically, GPCRsignalointia governs senses, mood, metabolism, cardiovascular and immune functions, among many others. In pharmacology, these receptors are prominent drug targets, with ligands that are agonists, antagonists, inverse agonists, or allosteric modulators.