opsin

noun

op·​sin ˈäp-sən 

: any of various colorless proteins that in combination with retinal or a related prosthetic group form a visual pigment (such as rhodopsin) in a reaction reversible by light

Examples of opsin in a Sentence

Recent Examples on the Web

This gene is different from the opsin genes that are found in their eyes. — Laura Baisas, Popular Science, 23 Aug. 2023

In a 2018 study, Schweikert and colleagues found the fish sensed light with their skin using a protein called opsin. — Will Sullivan, Smithsonian Magazine, 24 Aug. 2023

In an outpatient procedure, clinicians would inject an opsin gene into the nerve through a natural opening in the skull above the upper jaw. — New Atlas, 16 Jan. 2026

Instead of using amino acids—found in other animal opsins—ASO-II opsins employ chloride ions. — Maria Mocerino, Interesting Engineering, 7 Sep. 2025

Word History

Etymology

from -opsin (in porphyropsin and rhodopsin)

Note: Term introduced by the American physiologist George Wald (1906-97) in "The Chemistry of Rod Vision," Science, vol. 113, issue 2933, March 16, 1951, p. 287: "Rhodopsin and porphyropsin are carotenoid-proteins—proteins bearing carotenoid prosthetic groups to which they owe their color and sensitivity to light. Each of these pigments possesses a single type of prosthetic group. The protein probably varies from one animal to another; it may be called opsin, and named for the animal of origin."

First Known Use

1951, in the meaning defined above

Rhymes for opsin

• rhodopsin

Medical Definition

opsin

noun

op·​sin ˈäp-sən 

: 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