G-protein

biochemistry

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June 29, 2026

Quick Summary

G proteins are a class of cell membrane proteins that play a crucial role in transmitting signals from the cell surface into the cell's interior. These proteins are coupled to cell surface receptors. When a receptor is activated by an extracellular signaling molecule, such as a hormone or neurotransmitter, the G protein binds to GTP, forming an active complex. This complex then mediates an intracellular event, like activating other molecules within the cell.12

G protein-coupled receptors (GPCRs) are found in many organisms, including mammals, plants, and microorganisms. They respond to a wide array of substances, including light, hormones, and neurotransmitters. GPCRs are important targets for drug development, with medications like clozapine and salmeterol acting on specific GPCRs to treat conditions such as schizophrenia and asthma.2

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Alfred G. Gilman
…research in discovering molecules called G proteins. These are intermediaries in the multistep pathway cells use to react to an incoming signal, such as a hormone or neurotransmitter.
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…research in discovering molecules called G proteins. These are intermediaries in the multistep pathway cells use to react to an incoming signal, such as a hormone or neurotransmitter.
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Robert J. Lefkowitz
…an intracellular molecule called a G protein (guanine nucleotide-binding protein), which had been discovered earlier by American pharmacologist Alfred G. Gilman and American biochemist Martin Rodbell (Gilman and Rodbell shared the 1994 Nobel Prize for Physiology or Medicine for their independent discovery of G proteins). When activated, G proteins stimulate…
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…an intracellular molecule called a G protein (guanine nucleotide-binding protein), which had been discovered earlier by American pharmacologist Alfred G. Gilman and American biochemist Martin Rodbell (Gilman and Rodbell shared the 1994 Nobel Prize for Physiology or Medicine for their independent discovery of G proteins). When activated, G proteins stimulate…
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Martin Rodbell
…of natural signal transducers called G-proteins that help cells in the body communicate with each other. He shared the prize with American pharmacologist Alfred G. Gilman, who later proved Rodbell’s hypothesis by isolating the G-protein, which is so named because it binds to nucleotides called guanosine diphosphate and guanosine triphosphate,…
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…of natural signal transducers called G-proteins that help cells in the body communicate with each other. He shared the prize with American pharmacologist Alfred G. Gilman, who later proved Rodbell’s hypothesis by isolating the G-protein, which is so named because it binds to nucleotides called guanosine diphosphate and guanosine triphosphate,…
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