Phototransduction Pathway

Phototransduction is a biochemical process by which the photoreceptor cells generate electrical signals in response to captured photons. The vertebrate cascade starts with the absorption of photons by the photoreceptive pigments, the rhodopsins, which consist of a membrane embedded chromophore, 11-cis-retinal, and a G-protein-coupled receptor, opsin. The photon isomerizes 11-cis-retinal to all-trans-retinal which induces a structural change that activates the opsin. This triggers hydrolysis of cGMP by activating a transducin-phosphodiesterase 6 (PDE6) cascade, which results in closure of the cGMP-gated cation channels (CNG) in the plasma membrane and membrane hyperpolarization. The hyperpolarization of the membrane potential of the photoreceptor cell modulates the release of neurotransmitters to downstream cells. Recovery from light involves the deactivation of the light-activated intermediates: photolyzed rhodopsin is phosphorylated by rhodopsin kinase (RK) and subsequently capped off by arrestin; GTP-binding transducin alpha subunit deactivates through a process that is stimulated by RGS9. (NCI Thesaurus/KEGG)

YOU MAY ALSO LIKE

Phototoxicity

A condition in which the skin or eyes become very sensitive to sunlight or other forms of light. It can be caused…

Phototherapy

The treatment of disease with certain types of light. Phototherapy can use lasers, LED, fluorescent lamps, and ultraviolet or infrared radiation. Also…

Phototesting

Special tests used to measure the reaction of the skin to ultraviolet radiation. Phototesting is being used to see if drugs taken…

Photosynthesis

A chemical process that occurs in plants, algae, and some types of bacteria, when they are exposed to sunlight. During photosynthesis, water…

Photostability Test

An assay or diagnostic test utilized to measure the level of degradation of a drug or material in the presence of ultraviolet,…

Photostability Drug Study

A Photostability study would be a one time study.