An important class of intracellular signaling molecules that provide the link between activated receptor molecules (such as hormone or neurotransmitter receptors that are not ligand-gated ion channels) and subsequent biochemical events inside target cells. G-proteins are activated when they bind GTP in response to receptor activation.
a protein which has a role in controlling mechanisms within a cell. G proteins interact with adenylate cyclase in controlling the level of adenosine 3', 5' cyclic monophosphate (cAMP) within cells.
One of a group of switch proteins involved in a signaling system that passes incoming messages across cell membranes and within cells.
Any of numerous heterotrimeric guanine nucleotide-binding proteins that usually are linked to a seven-spanning receptor on the cell surface. Binding of hormone to the receptor converts the inactive form with GDP bound to the a subunit to the active Ga¡¿GTP form, which in turn stimulates or inhibits an effector protein that generates a second messenger or functions as an ion channel.
Intracellular regulatory molecules whose actions are instigated by neurotransmitters. Several types of G proteins exist, including stimulatory G proteins (Gs), which enhance the activities of enzymes, and inhibitory G proteins (Gi), which inhibit the activities of other enzymes.
One of a large family of heterotrimeric GTP-binding proteins that are important intermediaries in cell-signaling pathways. Usually activated by the binding of a hormone or other signaling ligand to a seven-pass transmembrane receptor protein.
A membrane protein involved in signal transduction; characterized by binding guanyl nucleotides. The activation of certain receptors activates the G protein, which in turn activates adenylate cyclase. G protein activation involves binding a GTP molecule in place of a GDP molecule.
A protein located on the inside of the cell membrane that helps transmit molecular signals into cells.
One of a group of proteins involved in signal transduction within the cell.
G proteins, short for guanine nucleotide binding proteins, are a family of proteins involved in second messenger cascades. They are so called because of their signaling mechanism, which uses the exchange of guanosine diphosphate (GDP) for guanosine triphosphate (GTP) as a general molecular "switch" function to regulate cell processes. Alfred Gilman and Martin Rodbell were awarded the Nobel Prize in Physiology or Medicine in 1994 for their discovery of and research on G proteins.