Guanine nucleotide-binding protein (G protein)

Guanine nucleotide-binding proteins, commonly called G proteins, are a superfamily of proteins functioning as molecular switches in cells, transmitting signals from various extracellular stimuli to intracellular responses[5]. Their activity depends on binding and hydrolyzing GTP and GDP. G proteins fall into two major classes: heterotrimeric G proteins (composed of alpha, beta, and gamma subunits) and small GTPases (monomeric, such as those in the Ras superfamily)[5]. Heterotrimeric G proteins are activated by G protein-coupled receptors (GPCRs), leading to a cascade of downstream signaling events affecting enzymes, ion channels, and cellular functions. Small GTPases also participate in signal transduction but regulate other processes such as cytoskeletal dynamics and vesicular trafficking. G proteins and their signaling pathways are central in controlling cell metabolism, growth, differentiation, and survival, making them important therapeutic targets or disease drivers in oncology, neurology, and other fields[5].

Other names

GTP-binding proteinGTPaseSmall GTPaseHeterotrimeric G proteinRas superfamily GTPase

Activation or inhibition of downstream effectors by binding/hydrolyzing GTP/GDP; Mediation of signals from GPCRs via subunit release (alpha, beta-gamma); Regulation of enzymatic activity and ion channel function through protein–protein interaction