Rhodopsin
(Redirected from Scotopsin)
Rhodopsin (also known as visual purple) is a type of photoreceptor cell in the eye that is responsible for the detection of light. It is a biological pigment found in the rods of the retina and is a G-protein-coupled receptor (GPCR).
Rhodopsin is extremely sensitive to light, and thus enables vision in low-light conditions. When exposed to light, the pigment immediately photobleaches, and it takes about 30 minutes to regenerate fully in humans.
Structure[edit | edit source]
Rhodopsin is composed of a protein moiety called opsin and a covalently bound cofactor called retinal, a photoreactive chromophore. Opsin is a seven-transmembrane domain protein, and its structure is primarily determined by its seven alpha helices.
Function[edit | edit source]
The primary function of rhodopsin is to detect light, which it does through a process called phototransduction. This process involves a series of steps:
- Absorption of a photon by the retinal component of rhodopsin.
- Isomerization of 11-cis-retinal to all-trans-retinal.
- Activation of the G protein transducin by the opsin component of rhodopsin.
- Activation of phosphodiesterase, which hydrolyzes cyclic GMP.
- Closure of cyclic GMP-gated ion channels in the plasma membrane, leading to hyperpolarization of the cell and transmission of the signal to the brain.
Clinical significance[edit | edit source]
Mutations in the gene encoding rhodopsin can lead to various forms of retinitis pigmentosa, a group of hereditary diseases that result in progressive vision loss. These mutations can affect the stability of the rhodopsin molecule, its ability to bind to 11-cis-retinal, or its ability to activate transducin.
See also[edit | edit source]
References[edit | edit source]
Rhodopsin Resources | |
---|---|
|
Search WikiMD
Ad.Tired of being Overweight? Try W8MD's physician weight loss program.
Semaglutide (Ozempic / Wegovy and Tirzepatide (Mounjaro / Zepbound) available.
Advertise on WikiMD
WikiMD's Wellness Encyclopedia |
Let Food Be Thy Medicine Medicine Thy Food - Hippocrates |
Translate this page: - East Asian
中文,
日本,
한국어,
South Asian
हिन्दी,
தமிழ்,
తెలుగు,
Urdu,
ಕನ್ನಡ,
Southeast Asian
Indonesian,
Vietnamese,
Thai,
မြန်မာဘာသာ,
বাংলা
European
español,
Deutsch,
français,
Greek,
português do Brasil,
polski,
română,
русский,
Nederlands,
norsk,
svenska,
suomi,
Italian
Middle Eastern & African
عربى,
Turkish,
Persian,
Hebrew,
Afrikaans,
isiZulu,
Kiswahili,
Other
Bulgarian,
Hungarian,
Czech,
Swedish,
മലയാളം,
मराठी,
ਪੰਜਾਬੀ,
ગુજરાતી,
Portuguese,
Ukrainian
Medical Disclaimer: WikiMD is not a substitute for professional medical advice. The information on WikiMD is provided as an information resource only, may be incorrect, outdated or misleading, and is not to be used or relied on for any diagnostic or treatment purposes. Please consult your health care provider before making any healthcare decisions or for guidance about a specific medical condition. WikiMD expressly disclaims responsibility, and shall have no liability, for any damages, loss, injury, or liability whatsoever suffered as a result of your reliance on the information contained in this site. By visiting this site you agree to the foregoing terms and conditions, which may from time to time be changed or supplemented by WikiMD. If you do not agree to the foregoing terms and conditions, you should not enter or use this site. See full disclaimer.
Credits:Most images are courtesy of Wikimedia commons, and templates Wikipedia, licensed under CC BY SA or similar.
Contributors: Prab R. Tumpati, MD