Gq alpha subunit

Gq protein or Gq/11 is a heterotrimeric G protein subunit that activates phospholipase C (PLC). PLC in turn hydrolyzes Phosphatidylinositol 4,5-bisphosphate (PIP2) to diacyl glycerol (DAG) and inositol triphosphate (IP3) signal transduction pathway. DAG acts as a second messenger that activates Protein Kinase C (PKC) and IP3 helps in phosphorylation of some proteins.

Function
Gq proteins are class of G proteins which work to activate phospholipase C (PLC), participating in a variety of cellular signaling pathways, including taste, manic depression, tumor promotion, etc.

The Gq protein works by activating PLC. PLC then cleaves a phospholipid. In the process, phosphatidylinositol 4,5-bisphosphate (PIP2) is cleaved into diacyl glycerol (DAG) and inositol 1,4,5-triphosphate (IP3). DAG remains bound to the membrane, and IP3 is released as a soluble structure into the cytosol. IP3 then diffuses through the cytosol to bind to IP3 receptors, particular calcium channels in the endoplasmic reticulum (ER). These channels are specific to calcium and only allow the passage of calcium to move through. This causes the cytosolic concentration of calcium to increase, causing a cascade of intracellular changes and activity.


 * Further reading:Calcium function in vertebrates

In addition, calcium and DAG together works to activate PKC, which goes on to phosphorylate other molecules, leading to altered cellular activity.


 * Further reading:function of protein kinase C

Examples of GPCR partners
From modulatory neurotransmitter receptors (amine receptors belonging to rhodopsin family), Gq is usually coupled to e.g. the G-protein coupled receptors:


 * 5-HT2 serotonergic receptors
 * Alpha-1 adrenergic receptor
 * Vasopressin type 1 receptor
 * Angiotensin II receptor type 1
 * Calcitonin receptor
 * Histamine H1 receptor
 * Metabotropic glutamate receptor, Group I
 * M 1, M 3, and M 5 muscarinic receptors

Genes

 * GNAQ,, ,

Mnemonics
An easy mnemonic used in medical school to remember which receptor utilizes the Gq subunit would be: "Kiss and Kick until you're sick of sex." (i.e. QISS and QIQ until you're SIQ of SQS.") QISS = adrenergic (alpha1, alpha2, beta1, beta2), QIQ (M1, M2, M3), SIQ (Dopamine1, dopamine2, Histamine1), SQS (Histamine 2, Vasopressin1, Vasopressin 2).


 * Gq = Q
 * Gi = I
 * Gs = S