The G_s alpha subunit (G_αs, G_sα) is a subunit of the

heterotrimeric G protein Heterotrimeric G protein, also sometimes referred to as the ''"large" G proteins'' (as opposed to the subclass of smaller, monomeric small GTPases) are membrane-associated G proteins that form a Heteromer, heterotrimeric complex. The biggest no ...

G_s that stimulates the

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. Discovery cAMP was discovered by Earl Sutherland ...

by activating

adenylyl cyclase Adenylate cyclase (EC 4.6.1.1, also commonly known as adenyl cyclase and adenylyl cyclase, abbreviated AC) is an enzyme with systematic name ATP diphosphate-lyase (cyclizing; 3′,5′-cyclic-AMP-forming). It catalyzes the following reaction: :A ...

. G_sα is a

GTPase GTPases are a large family of hydrolase enzymes that bind to the nucleotide guanosine triphosphate (GTP) and hydrolyze it to guanosine diphosphate (GDP). The GTP binding and hydrolysis takes place in the highly conserved P-loop "G domain", a pro ...

that functions as a cellular signaling protein. G_sα is the founding member of one of the four families of heterotrimeric G proteins, defined by the alpha subunits they contain: the G_αs family, G_αi/G_αo family, G_αq family, and G_α12/G_α13 family. The Gs-family has only two members: the other member is G_olf, named for its predominant expression in the olfactory system. In humans, G_sα is encoded by the GNAS complex locus, while G_olfα is encoded by the

GNAL Guanine nucleotide-binding protein G(olf) subunit alpha is a protein that in humans is encoded by the ''GNAL'' gene. Its main product is the heterotrimeric G-protein alpha subunit Golf-α, a member of the Gs alpha subunit family that is a key compo ...

gene.

Function

The general function of G_s is to activate intracellular signaling pathways in response to activation of cell surface G protein-coupled receptors (GPCRs). GPCRs function as part of a three-component system of receptor-transducer-effector. The transducer in this system is a

, composed of three subunits: a Gα protein such as G_sα, and a complex of two tightly linked proteins called Gβ and Gγ in a Gβγ complex. When not stimulated by a receptor, Gα is bound to

GDP Gross domestic product (GDP) is a monetary measure of the market value of all the final goods and services produced and sold (not resold) in a specific time period by countries. Due to its complex and subjective nature this measure is ofte ...

and to Gβγ to form the inactive G protein trimer. When the receptor binds an activating ligand outside the cell (such as a

hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...

neurotransmitter A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, any main body part or target cell, may be another neuron, but could also be a gland or muscle cell. Neuro ...

), the activated receptor acts as a

guanine nucleotide exchange factor Guanine nucleotide exchange factors (GEFs) are proteins or protein domains that activate monomeric GTPases by stimulating the release of guanosine diphosphate (GDP) to allow binding of guanosine triphosphate (GTP). A variety of unrelated structu ...

to promote GDP release from and GTP binding to Gα, which drives dissociation of GTP-bound Gα from Gβγ. In particular, GTP-bound, activated G_sα binds to

to produce the

second messenger Second messengers are intracellular signaling molecules released by the cell in response to exposure to extracellular signaling molecules—the first messengers. (Intercellular signals, a non-local form or cell signaling, encompassing both first me ...

cAMP Camp may refer to: Outdoor accommodation and recreation * Campsite or campground, a recreational outdoor sleeping and eating site * a temporary settlement for nomads * Camp, a term used in New England, Northern Ontario and New Brunswick to descri ...

, which in turn activates the cAMP-dependent protein kinase (also called Protein Kinase A or PKA). Cellular effects of G_sα acting through PKA are described

here Here is an adverb that means "in, on, or at this place". It may also refer to: Software * Here Technologies, a mapping company * Here WeGo (formerly Here Maps), a mobile app and map website by Here Technologies, Here Television * Here TV (form ...

. Although each GTP-bound G_sα can activate only one adenylyl cyclase enzyme, amplification of the signal occurs because one receptor can activate multiple copies of G_s while that receptor remains bound to its activating

agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...

, and each G_sα-bound adenylyl cyclase enzyme can generate substantial cAMP to activate many copies of PKA.

Receptors

The G protein-coupled receptors that couple to the G_s family proteins include: * 5-HT receptors types 5-HT₄ and 5-HT₇ *

ACTH receptor The adrenocorticotropic hormone receptor or ACTH receptor also known as the melanocortin receptor 2 or MC2 receptor is a type of melanocortin receptor (type 2) which is specific for ACTH. A G protein–coupled receptor located on the external ...

a.k.a. MC2R *

Adenosine receptor The adenosine receptors (or P1 receptors) are a class of purinergic G protein-coupled receptors with adenosine as the endogenous ligand. There are four known types of adenosine receptors in humans: A1, A2A, A2B and A3; each is encoded by a di ...

types A_2a and A_2b *

Arginine vasopressin receptor 2 Vasopressin receptor 2 (V2R), or arginine vasopressin receptor 2 (officially called AVPR2), is a protein that acts as receptor for vasopressin. AVPR2 belongs to the subfamily of G-protein-coupled receptors. Its activity is mediated by the Gs ty ...

* β-adrenergic receptors types β₁, β₂ and β₃ *

Calcitonin receptor The calcitonin receptor (CT) is a G protein-coupled receptor that binds the peptide hormone calcitonin and is involved in maintenance of calcium homeostasis, particularly with respect to bone formation and metabolism. CT works by activating the ...

Calcitonin gene-related peptide receptor Calcitonin receptor-like (CALCRL), also known as the calcitonin receptor-like receptor (CRLR), is a human protein; it is a receptor for calcitonin gene-related peptide. Function The protein encoded by the CALCRL gene is a G protein-coupled rec ...

Cannabinoid receptor 2 The cannabinoid receptor type 2, abbreviated as CB2, is a G protein-coupled receptor from the cannabinoid receptor family that in humans is encoded by the ''CNR2'' gene. It is closely related to the cannabinoid receptor type 1 (CB1), which is la ...

Corticotropin-releasing hormone receptor Corticotropin-releasing hormone receptors (CRHRs), also known as corticotropin-releasing factor receptors (CRFRs) are a G protein-coupled receptor family that binds corticotropin-releasing hormone (CRH). There are two receptors in the family, ...

Dopamine receptors Dopamine receptors are a class of G protein-coupled receptors that are prominent in the vertebrate central nervous system (CNS). Dopamine receptors activate different effectors through not only G-protein coupling, but also signaling through diffe ...

D₁-like family ( D₁ and D₅), mainly through G_olf in the

striatum The striatum, or corpus striatum (also called the striate nucleus), is a nucleus (a cluster of neurons) in the subcortical basal ganglia of the forebrain. The striatum is a critical component of the motor and reward systems; receives glutamate ...

* FSH-receptor *

Gastric inhibitory polypeptide receptor The gastric inhibitory polypeptide receptor (GIP-R), also known as the glucose-dependent insulinotropic polypeptide receptor, is a protein that in humans is encoded by the ''GIPR'' gene. GIP-R is a member of the 7-transmembrane protein family, a ...

Glucagon receptor The glucagon receptor is a 62 kDa protein that is activated by glucagon and is a member of the class B G-protein coupled family of receptors, coupled to G alpha i, Gs and to a lesser extent G alpha q. Stimulation of the receptor results in the ...

* Growth-hormone-releasing hormone receptor * Histamine H₂ receptor *

Luteinizing hormone/choriogonadotropin receptor The luteinizing hormone/choriogonadotropin receptor (LHCGR), also lutropin/choriogonadotropin receptor (LCGR) or luteinizing hormone receptor (LHR) is a transmembrane receptor found predominantly in the ovary and testis, but also many extragonad ...

Melanocortin receptor Melanocortin receptors are members of the rhodopsin family of 7-transmembrane G protein-coupled receptors. There are five known members of the melanocortin receptor system each with differing specificities for melanocortins: * . MC1R is associat ...

MC1R The melanocortin 1 receptor (MC1R), also known as melanocyte-stimulating hormone receptor (MSHR), melanin-activating peptide receptor, or melanotropin receptor, is a G protein–coupled receptor that binds to a class of pituitary peptide hormones ...

MC2R The adrenocorticotropic hormone receptor or ACTH receptor also known as the melanocortin receptor 2 or MC2 receptor is a type of melanocortin receptor (type 2) which is specific for ACTH. A G protein–coupled receptor located on the external cel ...

(a.k.a. ACTH receptor),

MC3R Melanocortin 3 receptor (MC3R) is a protein that in humans is encoded by the gene. Function This gene encodes MC3R, a G-protein coupled receptor (GPCR) for melanocyte-stimulating hormone (MSH) and adrenocorticotropic hormone (ACTH) that is exp ...

, MC4R, MC5R *

Olfactory receptors Olfactory receptors (ORs), also known as odorant receptors, are chemoreceptors expressed in the cell membranes of olfactory receptor neurons and are responsible for the detection of odorants (for example, compounds that have an odor) which give ri ...

, through G_olf in the olfactory neurons *

Parathyroid hormone receptor 1 Parathyroid hormone/parathyroid hormone-related peptide receptor, also known as parathyroid hormone 1 receptor (PTH1R), is a protein that in humans is encoded by the ''PTH1R'' gene. PTH1R functions as a receptor for parathyroid hormone ( PTH) and f ...

Prostaglandin receptor Prostaglandin receptors or prostanoid receptors represent a sub-class of cell surface membrane Receptor (biochemistry), receptors that are regarded as the primary receptors for one or more of the classical, naturally occurring prostanoids viz., pros ...

types D₂ and I₂ *

Secretin receptor Human secretin receptor (gene name SCTR) is a G protein-coupled receptor which binds secretin and is the leading member (''i.e.'', first cloned) of the class B GPCR subfamily. Interactions Secretin receptor has been shown to interact with pitui ...

Thyrotropin receptor The thyrotropin receptor (or TSH receptor) is a receptor (and associated protein) that responds to thyroid-stimulating hormone (also known as "thyrotropin") and stimulates the production of thyroxine (T4) and triiodothyronine (T3). The TSH recep ...

Trace amine-associated receptor 1 Trace amine-associated receptor 1 (TAAR1) is a trace amine-associated receptor (TAAR) protein that in humans is encoded by the ''TAAR1'' gene. TAAR1 is an intracellular amine-activated and G protein-coupled receptor (GPCR) that is primarily ex ...

References

External links

* * * {{Portal bar, Biology, border=no * Peripheral membrane proteins Medical mnemonics

Function

Receptors

See also

References

External links