Gproteinkopplade

Gproteinkopplade, known in English as G protein-coupled receptors (GPCRs), are a vast and diverse family of cell-surface receptors that detect a wide array of extracellular signals. They play central roles in virtually all physiological processes and are major targets for therapeutic drugs.

GPCRs share a characteristic structure of seven transmembrane α-helices with extracellular N-terminus and intracellular C-terminus. Ligand binding induces conformational changes that enable coupling to heterotrimeric G proteins (Gα, Gβ, Gγ). Upon activation, Gα exchanges GDP for GTP and dissociates from Gβγ, regulating enzymes such as adenylyl cyclase and phospholipase C to generate second messengers like cAMP, IP3, and DAG. Desensitization involves GPCR kinases and β-arrestins, which can also initiate alternative signaling routes.

GPCRs are traditionally grouped into classes A to F, with class A (rhodopsin-like) the largest. They respond to photons, amines, peptides, lipids, and other molecules, or to volatile signals in olfaction. Some GPCRs are constitutively active or modulated allosterically.

GPCRs are targets for roughly a third of all marketed drugs, including agonists, antagonists, inverse agonists, and allosteric modulators. They influence cardiovascular, nervous, metabolic, and sensory systems, and their dysfunction is implicated in diseases ranging from hypertension to neurodegenerative disorders.

The GPCR–G protein signaling axis was established in the late 20th century, leading to Nobel Prizes for Alfred G. Gilman and Martin Rodbell in 1994, and for Robert Lefkowitz and Brian Kobilka in 2012 for studies of GPCR structure and function.