G-protein

In signalling pathways, G-proteins act as transducers and convert signals from one form to another form, by binding to other proteins in the plasma membrane of a cell. They can bind GTP or GDP. G-proteins can be either trimeric or monomeric. Monomeric G-proteins transduce signals from enzyme-linked receptors whereas trimeric G-proteins transduce signals from G-protein linked receptors . Ion channels can be activated by binding of G-proteins. This can slow the heart beat when G-proteins bind to muscarinic receptors, as they increase the permeability of a neurone to K+ ions, which decreases the rate of neurone firing .