Ion channel regulation by G proteins.
Ion channels are poised uniquely to initiate, mediate, or regulate such distinct cellular activities as action potential propagation, secretion, and gene transcription. In retrospect, it is not surprising that studies of ion channels have revealed considerable diversities in their primary structures, regulation, and expression. From a functional standpoint, the various mechanisms coopted by cells to regulate channel activity are particularly fascinating. Extracellular ligands, membrane potential, phosphorylation, ions themselves, and diffusible second messengers are all well-established regulators of ion channel activity. Heterotrimeric GTP-binding proteins (G proteins) mediate many of these types of ion channel regulation by stimulating or inhibiting phosphorylation pathways, initiating intracellular cascades leading to elevation of cytosolic Ca2+ or adenosine 3',5'-cyclic monophosphate levels, or by generating various lipid-derived compounds. In some cases, it seems that activated G protein subunits can interact directly with ion channels to elicit regulation. Although there is currently little direct biochemical evidence to support such a mechanism, it is the working hypothesis for the most-studied G protein-regulated ion channels.
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D015220:Calcium Channels / Q000502:physiology; D002462:Cell Membrane / Q000502:physiology; D019204:GTP-Binding Proteins / Q000502:physiology*; D006321:Heart / Q000502:physiology; D006706:Homeostasis; D006801:Humans; D007473:Ion Channels / Q000502:physiology*; D008024:Ligands; D008322:Mammals; D015221:Potassium Channels / Q000502:physiology; D011956:Receptors, Cell Surface / Q000502:physiology*; D015290:Second Messenger Systems; D015398:Signal Transduction
D015220:Calcium Channels; D007473:Ion Channels; D008024:Ligands; D015221:Potassium Channels; D011956:Receptors, Cell Surface; D019204:GTP-Binding Proteins