Photoreceptor protein: Difference between revisions

Photoreceptor proteins typically consist of a [[protein]] attached to a non-protein [[chromophore]] (sometimes referred as [[photopigment]], thateven so photopigment may also refer to the photoreceptor as a whole). The chromophore reacts to light via [[photoisomerization]] or [[photoreduction]], thus initiating a change of the receptor protein which triggers a [[signal transduction]] cascade. PigmentsChromophores found in photoreceptors include [[retinal]] ([[retinylidene protein]]s, for example [[rhodopsin]] in animals),<ref>{{Cite web|title=Rhodopsin {{!}} biochemistry|url=https://www.britannica.com/science/rhodopsin|access-date=2021-01-21|website=Encyclopedia Britannica|language=en}}</ref> [[Flavin group|flavin]] ([[flavoprotein]]s, for example [[cryptochrome]] in plants and animals)<ref>{{Cite journal|last1=Lin|first1=Chentao|last2=Todo|first2=Takeshi|date=2005-04-29|title=The cryptochromes|journal=Genome Biology|volume=6|issue=5|pages=220|doi=10.1186/gb-2005-6-5-220|pmid=15892880|pmc=1175950|issn=1474-760X|doi-access=free}}</ref> and [[Bilin (biochemistry)|bilin]] ([[biliprotein]]s, for example [[phytochrome]] in plants).<ref>{{Cite journal|last1=Rockwell|first1=Nathan C.|last2=Su|first2=Yi-Shin|last3=Lagarias|first3=J. Clark|date=2006|title=Phytochrome structure and signaling mechanisms|url=https://pubmed.ncbi.nlm.nih.gov/16669784/|journal=Annual Review of Plant Biology|volume=57|pages=837–858|doi=10.1146/annurev.arplant.56.032604.144208|issn=1543-5008|pmc=2664748|pmid=16669784}}</ref> The plant protein [[UVR8]] is exceptional amongst photoreceptors in that it contains no external photopigmentchromophore. Instead, UVR8 absorbs light through [[tryptophan]] residues within its protein [[coding sequence]].<ref>{{Cite journal|last1=Li|first1=Xiankun|last2=Ren|first2=Haisheng|last3=Kundu|first3=Mainak|last4=Liu|first4=Zheyun|last5=Zhong|first5=Frank W.|last6=Wang|first6=Lijuan|last7=Gao|first7=Jiali|last8=Zhong|first8=Dongping|date=2020-08-28|title=A leap in quantum efficiency through light harvesting in photoreceptor UVR8|url=https://www.nature.com/articles/s41467-020-17838-6 |journal=Nature Communications|language=en|volume=11|issue=1|pages=4316|doi=10.1038/s41467-020-17838-6|pmid=32859932|pmc=7455749|bibcode=2020NatCo..11.4316L|issn=2041-1723|doi-access=free}}</ref>

''(Also{{See see: [[also|Photoreceptor cell]])''}}

*[[OPN5]]: sensitive to [[UV-light]]<ref>{{cite journal |last1=Kojima |first1=Daisuke |last2=Mori |first2=Suguru |last3=Torii |first3=Masaki |last4=Wada |first4=Akimori |last5=Morishita |first5=Rika |last6=Fukada |first6=Yoshitaka |title=UV-Sensitive Photoreceptor Protein OPN5 in Humans and Mice |journal=PLOS ONE |date=17 October 2011 |volume=6 |issue=10 |pages=e26388 |doi=10.1371/journal.pone.0026388 |pmid=22043319 |pmc=3197025 |bibcode=2011PLoSO...626388K |doi-access=free }}</ref>

All the photoreceptors listed above allow plants to sense light with wavelengths range from 280&nbsp;[[nanometre|nm]] (UV-B) to 750&nbsp;nm (far-red light). Plants use light of different wavelengths as environmental cues to both alter their position and to trigger important developmental transitions.<ref>{{cite journal |last1=Galvão |first1=Vinicius Costa |last2=Fankhauser |first2=Christian |s2cid=12390801 |title=Sensing the light environment in plants: photoreceptors and early signaling steps |journal=Current Opinion in Neurobiology |date=October 2015 |volume=34 |pages=46–53 |doi=10.1016/j.conb.2015.01.013 |pmid=25638281 |url=https://zenodo.org/record/161783 }}</ref> The most prominent wavelength responsible for plant mechanisms is blue light, which can trigger cell elongation, plant orientation, and flowering.<ref>{{Cite journal|last1=Christie|first1=John M.|last2=Briggs|first2=Winslow R.|date=2001-04-13|title=Blue Light Sensing in Higher Plants *|url=https://www.jbc.org/article/S0021-9258(19)46006-7/abstract|journal=Journal of Biological Chemistry|language=English|volume=276|issue=15|pages=11457–11460|doi=10.1074/jbc.R100004200|issn=0021-9258|pmid=11279226|doi-access=free}}</ref> One of the most important processes regulated by photoreceptors is known as [[photomorphogenesis]]. When a seed germinates underground in the absence of light, its stem rapidly elongates upwards. When it breaks through the surface of the soil, photoreceptors perceive light. The activated photoreceptors cause a change in developmental program; the plant starts producing chlorophyll and switches to photosynthetic growth.<ref>{{cite journal |last1=Briggs |first1=Winslow R. |last2=Olney |first2=Margaret A. |title=Photoreceptors in Plant Photomorphogenesis to Date. Five Phytochromes, Two Cryptochromes, One Phototropin, and One Superchrome |journal=Plant Physiology |date=1 January 2001 |volume=125 |issue=1 |pages=85–88 |doi=10.1104/pp.125.1.85 |pmid=11154303 |pmc=1539332 |doi-access=free }}</ref>