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Photopigments are unstable pigments that undergo a physical or chemical change in the presence of light. The term is generally applied to the non-protein chromophore moiety of photosensitive chromoproteins, such as the pigments involved in photosynthesis and photoreception. In medical terminology, "photopigment" commonly refers to the photoreceptor proteins of the retina.

Photoreceptor pigments[]

Main article: Photoreceptor protein

The pigments in photoreceptor proteins either change their conformation or undergo photoreduction when they absorb a photon. This change in the conformation or redox state of the chromophore then affects the protein conformation or activity and triggers a signal transduction cascade. Examples for photoreceptor pigments include retinal (for example in rhodopsin), flavin (for example in cryptochrome), and bilin (for example in phytochrome).

Photopigments of the vertebrate retina[]

Main article: Opsin

In medical terminology, the term photopigment is applied to opsin-type photoreceptor proteins, specifically rhodopsin and photopsins, the photoreceptor proteins in the retinal rods and cones of vertebrates that are responsible for visual perception, but also melanopsin and others.

See also[]

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