Editing G protein-coupled receptor (section)

==Physiological roles==
GPCRs are involved in a wide variety of physiological processes. Some examples of their physiological roles include:
# The visual sense: The [[opsin]]s use a [[photoisomerization]] reaction to translate [[electromagnetic radiation]] into cellular signals. [[Rhodopsin]], for example, uses the conversion of [[Retinal|''11-cis''-retinal]] to [[Retinal|''all-trans''-retinal]] for this purpose.{{cn|date=April 2025}}
# The gustatory sense (taste): GPCRs in taste cells mediate release of [[gustducin]] in response to bitter-, umami- and sweet-tasting substances.{{cn|date=April 2025}}
# The sense of smell: Receptors of the [[olfactory epithelium]] bind odorants (olfactory receptors) and pheromones (vomeronasal receptors){{cn|date=April 2025}}
# Behavioral and mood regulation: Receptors in the [[mammal]]ian [[brain]] bind several different [[neurotransmitter]]s, including [[serotonin]], [[dopamine]], [[histamine]], [[Gamma-aminobutyric acid|GABA]], and [[glutamate]]
# Regulation of [[immune system]] activity and [[inflammation]]: [[chemokine]] receptors bind ligands that mediate intercellular communication between cells of the immune system; receptors such as [[histamine receptor]]s bind [[inflammatory mediators]] and engage target cell types in the [[Inflammation|inflammatory response]]. GPCRs are also involved in immune-modulation, e. g. regulating interleukin induction<ref>{{cite journal | vauthors = Saroz Y, Kho DT, Glass M, Graham ES, Grimsey NL | title = Cannabinoid Receptor 2 (CB<sub>2</sub>) Signals via G-alpha-s and Induces IL-6 and IL-10 Cytokine Secretion in Human Primary Leukocytes | journal = ACS Pharmacology & Translational Science | volume = 2 | issue = 6 | pages = 414–428 | date = December 2019 | pmid = 32259074 | doi = 10.1021/acsptsci.9b00049 | pmc = 7088898 | doi-access = free }}</ref> or suppressing [[Toll-like receptor|TLR]]-induced immune responses from T cells.<ref>{{cite journal | vauthors = Sharma N, Akhade AS, Qadri A | title = Sphingosine-1-phosphate suppresses TLR-induced CXCL8 secretion from human T cells | journal = Journal of Leukocyte Biology | volume = 93 | issue = 4 | pages = 521–8 | date = April 2013 | pmid = 23345392 | doi = 10.1189/jlb.0712328 | s2cid = 21897008 | doi-access =  }}</ref>
# Autonomic nervous system transmission: Both the [[sympathetic nervous system|sympathetic]] and [[parasympathetic nervous system|parasympathetic]] nervous systems are regulated by GPCR pathways, responsible for control of many automatic functions of the body such as blood pressure, heart rate, and digestive processes{{cn|date=April 2025}}
# Cell density sensing: A novel GPCR role in regulating cell density sensing.
# Homeostasis modulation (e.g., water balance).<ref name="pmid21802439">{{cite journal | vauthors = Hazell GG, Hindmarch CC, Pope GR, Roper JA, Lightman SL, Murphy D, O'Carroll AM, Lolait SJ | title = G protein-coupled receptors in the hypothalamic paraventricular and supraoptic nuclei--serpentine gateways to neuroendocrine homeostasis | journal = Frontiers in Neuroendocrinology | volume = 33 | issue = 1 | pages = 45–66 | date = January 2012 | pmid = 21802439 | pmc = 3336209 | doi = 10.1016/j.yfrne.2011.07.002 }}</ref>
# Involved in growth and [[metastasis]] of some types of [[tumor]]s.<ref>{{cite journal | vauthors = Dorsam RT, Gutkind JS | title = G-protein-coupled receptors and cancer | journal = Nature Reviews. Cancer | volume = 7 | issue = 2 | pages = 79–94 | date = February 2007 | pmid = 17251915 | doi = 10.1038/nrc2069 | s2cid = 10996598 }}</ref>
# Used in the endocrine system for peptide and amino-acid derivative hormones that bind to GCPRs on the cell membrane of a target cell. This activates cAMP, which in turn activates several kinases, allowing for a cellular response, such as transcription.