The protein portion of the rhodopsin molecule; at least three separate opsins are located in cone cells.
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op·sin 'äp-sən n any of various colorless proteins that in combination with retinal or a related prosthetic group form a visual pigment (as rhodopsin) in a reaction which is reversed by light
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op·sin (opґsin) a protein of the retinal rods (scotopsin) and cones (photopsin) that combines with 11-cis-retinal (q.v.) to form visual pigments. The opsins are also named according to the color of pigment: iodopsin (violet), rhodopsin (purple), etc. See illustration at visual cycle, under cycle.Medical dictionary. 2011.