G protein

G proteins are a family of guanine nucleotide-binding proteins that function as molecular switches inside cells. They play a central role in transmitting signals from various extracellular stimuli to the cell's interior, thereby regulating numerous physiological processes. Their activity is controlled by their ability to bind and hydrolyze guanosine triphosphate (GTP) to guanosine diphosphate (GDP). There are two main classes: Monomeric small GTPases and Heterotrimeric G protein complexes (alpha, beta, gamma subunits). Activation involves ligand binding to GPCR, GDP release and GTP binding to the alpha subunit, leading to dissociation and downstream effector activation. Signal termination occurs via GTP hydrolysis.

Other names

Guanine nucleotide-binding proteins

G protein modulation via GPCR interaction or direct G protein targeting