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Rhodopsin kinase

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G protein-coupled receptor kinase 1
Identifiers
Symbol	GRK1
Alt. symbols	RHOK
Entrez	6011
HUGO	10013
OMIM	180381
RefSeq	NM_002929
UniProt	Q15835
Other data
EC number	2.7.11.14
Locus	Chr. 13 q34

Rhodopsin kinase (EC 2.7.11.14, cone opsin kinase, G-protein-coupled receptor kinase 1, GPCR kinase 1, GRK1, GRK7, opsin kinase, opsin kinase (phosphorylating), rhodopsin kinase (phosphorylating), RK, STK14) is a serine/threonine-specific protein kinase involved in phototransduction.^{[1][2][3][4][5][6][7][8]} This enzyme catalyses the following chemical reaction

ATP + rhodopsin ADP + phosphorhodopsin

Mutations in rhodopsin kinase are associated with a form of night blindness called Oguchi disease.^[9]

See also[edit | edit source]

• Rhodopsin
• Beta adrenergic receptor kinase
• G-protein coupled receptor kinases

References[edit | edit source]

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Begin Critique

Appropriate/Reliable Reference: Rhodopsin kinase is an extremely short article and really only has two facts written regarding this kinase. For these two facts there are 9 references in total used however, for the fact regarding the numerous names of this kinase there are 8. The fact that this exists is questionable. Considering there are technically only 2 facts and references are low this is a good article for editing.

Relevance: The few facts stated in this article are relevant, however very low quality. There is only an equation written and the numerous names of rhodopsin kinase. There are various things I can think of to add to this article to make it stronger for Wikipedia.

Neutrality: For this article, it is very neutral considering there are no opinions based nor are the facts stated liable to be biased. This seems pretty good for not starting any arguments with editors.

Viewpoints: Considering the only things mentioned in this article are the various names and the chemical reaction that occurs with rhodopsin kinase this is underrepresented overall. There are more applications for rhodopsin kinase in the cell. For example I could talk about the mechanism that rhodopsin kinase is involved with in the eye specifically with rod cells. We have the notes on this light-activated rhodopsin pathway as well as a section in our text that I could use and further support with peer reviewed sources how rhodopsin kinase inhibits rhodopsin and how this works in rod cells. I would do a step-by-step of this mechanism and the downstream effects involved. Aside from this mechanism I'm sure I can find more about rhodopsin is regulated and much more to make this article much stronger. w

Addition to Article

Rhodopsin Kinase is involved in mammalian rod cells specifically with photo transduction. G coupled-protein receptor kinases are the family that rhodopsin kinase belong to(14). This kinase is referred to as GRK1 and phosphorylates rhodopsin resulting in partial photo-activation of rhodopsin activating the dim flash response(10). Dim flash response is activated in dim light and its ideal to de-activate the rod cell photoreceptor or rhodopsin over time(12). GRK1 AND GRK7 exist and are isoforms of rhodopsin kinase. Studies have proven that in mice rod cells, GRK1 has competition with arrestin-1 for the binding site of rhodopsin(10). Arrestin-1 when bound to rhodopsin inhibits signaling and turns off photo-transduction completely(11). As with any enzyme, rhodopsin kinase has a regulator or inhibitor known as recoverin. In the dark state of the rod cells recoverin inhibits rhodopsin kinase. Specifically, a study has proven that GRK1 acts on the cytoplasmic loops of rhodopsin both the second and third loops. The cytoplasmic loops act specifically where transducin binds to rhodopsin so this allows GRK1 and transducin to compete for the binding site on rhodopsin. With recoverin present, it exists between GRK1 and rhodopsin and it was shown that when bound competition between GRK1 and transducin suppressed(13).

References:

(10) Sakurai, K., Chen, J., Khani, S.C., and Kefalov, V.J. (2015). Regulation of Mammalian Cone Phototransduction by Recoverin and Rhodopsin Kinase. J. Biol. Chem. 290, 9239–9250. (http://www.jbc.org.webdb.plattsburgh.edu:2048/content/290/14/9239.ful)

(11) Lodish textbook

(12) Sakurai, K., Young, J.E., Kefalov, V.J., and Khani, S.C. (2011). Variation in Rhodopsin Kinase Expression Alters the Dim Flash Response Shut Off and the Light Adaptation in Rod Photoreceptors. Invest. Ophthalmol. Vis. Sci. 52, 6793–6800.( https://www.ncbi.nlm.nih.gov/pubmed/21474765)

(13) Komolov, K.E., Senin, I.I., Kovaleva, N.A., Christoph, M.P., Churumova, V.A., Grigoriev, I.I., Akhtar, M., Philippov, P.P., and Koch, K.-W. (2009). Mechanism of rhodopsin kinase regulation by recoverin. Journal Of Neurochemistry 110, 72–79. (http://eds.b.ebscohost.com.webdb.plattsburgh.edu:2048/eds/pdfviewer/pdfviewer?sid=b28f4c2e-34fe-4647-8a13-19692f9d8fd7%40sessionmgr103&vid=2&hid=114)

(14) Regulation of the methylation status of G protein-...: Full Text Finder Results. (http://eds.b.ebscohost.com.webdb.plattsburgh.edu:2048/eds/detail/detail?vid=2&sid=dfc8061b-cfd7-4c97-ace1-16e8aea058a8%40sessionmgr104&hid=114&bdata=JnNpdGU9ZWRzLWxpdmUmc2NvcGU9c2l0ZQ%3d%3d#AN=22846544&db=mnh)