Gi alpha subunit
Encyclopedia
Gi alpha subunit is a heterotrimeric G protein
subunit that inhibits the production of cAMP
from ATP
.
Gi mainly inhibits the cAMP dependent pathway
by inhibiting adenylate cyclase activity, decreasing the production of cAMP
from ATP
, which, in turn, results in decreased activity of cAMP-dependent protein kinase
. Therefore, the ultimate effect of Gi is the opposite of cAMP-dependent protein kinase.
It is also attributed a minor role in activation of the phospholipase C pathway. Growth hormone is required for normal postnatal growth, bone growth, regulatory effects on protein, carbohydrate, and lipid metabolism. although this is mainly a function of the Gq alpha subunit
.
Heterotrimeric G protein
"G protein" usually refers to the membrane-associated heterotrimeric G proteins, sometimes referred to as the "large" G proteins. These proteins are activated by G protein-coupled receptors and are made up of alpha , beta and gamma subunits, the latter two referred to as the beta-gamma...
subunit that inhibits the production of cAMP
Cyclic adenosine monophosphate
Cyclic adenosine monophosphate is a second messenger important in many biological processes...
from ATP
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...
.
Receptors
The following G protein-coupled receptors couple to the Gi subunit:- AcetylcholineAcetylcholineThe chemical compound acetylcholine is a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans...
M2Muscarinic acetylcholine receptor M2The muscarinic acetylcholine receptor M2, also known as the cholinergic receptor, muscarinic 2, is a muscarinic acetylcholine receptor.-Heart:...
& M4Muscarinic acetylcholine receptor M4The muscarinic acetylcholine receptor M4, also known as the cholinergic receptor, muscarinic 4 , is a protein that, in humans, is encoded by the CHRM4 gene.-Function:...
receptors - Adenosine A1 & A3 receptors
- AdrenergicAdrenergicAn adrenergic agent is a drug, or other substance, which has effects similar to, or the same as, epinephrine . Thus, it is a kind of sympathomimetic agent...
α2A, α2B, & α2C receptors - ApelinApelinApelin is a peptide that in humans is encoded by the APLN gene. Apelin is the endogenous ligand for the G-protein-coupled APJ receptor that is expressed at the surface of some cell types...
receptors - Calcium-sensing receptorCalcium-sensing receptorThe calcium-sensing receptor is a Class C G-protein coupled receptor which senses extracellular levels of calcium ion. In the parathyroid gland, the calcium-sensing receptor controls calcium homeostasis by regulating the release of parathyroid hormone .-Signal transduction:The release of PTH is...
- ChemokineChemokineChemokines are a family of small cytokines, or proteins secreted by cells. Their name is derived from their ability to induce directed chemotaxis in nearby responsive cells; they are chemotactic cytokines...
CXCR4CXCR4C-X-C chemokine receptor type 4 also known as fusin or CD184 is a protein that in humans is encoded by the CXCR4 gene.- Function :...
receptor - DopamineDopamineDopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
D2, D3, D4 - GABAB receptor
- Glutamate mGluR2, mGluR3, mGluR4, mGluR6, mGluR7, & mGluR8 receptors
- HistamineHistamineHistamine is an organic nitrogen compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by...
H3 & H4 receptors - MelatoninMelatoninMelatonin , also known chemically as N-acetyl-5-methoxytryptamine, is a naturally occurring compound found in animals, plants, and microbes...
MT1, MT2, & MT3 receptors - OpioidOpioidAn opioid is a psychoactive chemical that works by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract...
δDelta Opioid receptorThe δ-opioid receptors, also known as delta opioid receptor or simply delta receptor, abbreviated DOR, is an opioid receptor that has enkephalins as its endogenous ligands.-Function:...
, κKappa Opioid receptorThe κ-opioid receptor is a protein that in humans is encoded by the OPRK1 gene. The κ-opioid receptor is one of five related receptors that bind opium-like compounds in the brain and are responsible for mediating the effects of these compounds...
, μMu Opioid receptorThe μ-opioid receptors are a class of opioid receptors with high affinity for enkephalins and beta-endorphin but low affinity for dynorphins. They are also referred to as μ opioid peptide receptors. The prototypical μ receptor agonist is the opium alkaloid morphine; μ refers to morphine...
, & nociceptinNociceptin receptorThe nociceptin receptor or NOP also known as the orphanin FQ receptor or kappa-type 3 opioid receptor is a protein that in humans is encoded by the OPRL1 gene. The nociceptin receptor is a G protein-coupled receptor whose natural ligand is known as nociceptin or orphanin FQ, a 17 amino acid...
receptors - ProstaglandinProstaglandinA prostaglandin is any member of a group of lipid compounds that are derived enzymatically from fatty acids and have important functions in the animal body. Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring....
EP1, EP3, FP, & TPThromboxane receptorThe thromboxane receptor is a protein on the surface of cells in the endothelium of blood vessels and in the placenta which interacts with the eicosanoid lipid thromboxane. It is a G-protein coupled receptor coupled to the G protein Gq.-Gene:...
receptors - SerotoninSerotoninSerotonin or 5-hydroxytryptamine is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system of animals including humans...
5-HT1 & 5-HT5 receptors
Function
See also: function of cAMP-dependent protein kinaseGi mainly inhibits the cAMP dependent pathway
CAMP dependent pathway
In the field of molecular biology, the cAMP-dependent pathway, also known as the adenylyl cyclase pathway, is a G protein-coupled receptor-triggered signaling cascade used in cell communication.-Mechanism:...
by inhibiting adenylate cyclase activity, decreasing the production of cAMP
Cyclic adenosine monophosphate
Cyclic adenosine monophosphate is a second messenger important in many biological processes...
from ATP
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...
, which, in turn, results in decreased activity of cAMP-dependent protein kinase
CAMP-dependent protein kinase
In cell biology, Protein kinase A refers to a family of enzymes whose activity is dependent on cellular levels of cyclic AMP . PKA is also known as cAMP-dependent protein kinase...
. Therefore, the ultimate effect of Gi is the opposite of cAMP-dependent protein kinase.
It is also attributed a minor role in activation of the phospholipase C pathway. Growth hormone is required for normal postnatal growth, bone growth, regulatory effects on protein, carbohydrate, and lipid metabolism. although this is mainly a function of the Gq alpha subunit
Gq alpha subunit
Gq protein or Gq/11 is a heterotrimeric G protein subunit that activates phospholipase C . PLC in turn hydrolyzes Phosphatidylinositol 4,5-bisphosphate to diacyl glycerol and inositol triphosphate signal transduction pathway...
.