G protein activity

Definition

Target type: molecularfunction

A molecular function regulator that cycles between active GTP-bound and inactive GDP-bound states. In its active state, binds to a variety of effector proteins to regulate cellular processes. Intrinsic GTPase activity returns the G protein to its GDP-bound state. The return to the GDP-bound state can be accelerated by the action of a GTPase-activating protein (GAP). [PMID:16923326, PMID:24470015]

G protein activity refers to the ability of G proteins, a family of proteins that act as molecular switches within cells, to bind and hydrolyze guanosine triphosphate (GTP). This process is central to signal transduction pathways, where extracellular signals are received by cell surface receptors and transduced into intracellular responses. G proteins consist of three subunits: alpha, beta, and gamma. The alpha subunit binds GTP and possesses intrinsic GTPase activity, allowing it to cycle between an active GTP-bound state and an inactive GDP-bound state. In the inactive state, the alpha subunit is associated with the beta and gamma subunits, forming a heterotrimeric complex. Upon activation by an extracellular signal, the receptor interacts with the G protein, triggering the exchange of GDP for GTP on the alpha subunit. This conformational change causes the alpha subunit to dissociate from the beta-gamma complex, allowing both subunits to interact with downstream effector proteins. The effector proteins, which are typically enzymes or ion channels, are activated or inhibited by the alpha or beta-gamma subunits, ultimately leading to changes in cellular function. The GTPase activity of the alpha subunit ensures that the activated state is transient, allowing for precise temporal control of signaling. The hydrolysis of GTP to GDP returns the alpha subunit to its inactive state, promoting reassociation with the beta-gamma complex and terminating the signal. The diversity of G protein subtypes and their interactions with a wide range of receptors and effectors provide a sophisticated mechanism for regulating a multitude of cellular processes, including cell growth, differentiation, metabolism, and neurotransmission.'
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Proteins (12)

Compounds (3,335)