retinal protein formed by the action of light on rhodopsin
The protein component of a photopigment. Different opsins give rise to photopigments with different spectral absorption characteristics and consequently account for the differences in spectral sensitivity of the various photoreceptor types. (See chromophore.)
Protein portion of the visual pigment of rod cells.
Opsins are a group of light-sensitive 35-55 kDa membrane-bound G protein-coupled receptors found in photoreceptor cells of the retina. They are involved in vision, mediating the conversion of a photon of light into an electrochemical signal, the first step in the visual transduction cascade. Two families of opsins are generally recognized due to different spatial expression and evolutionary histories.