the protein part of visual photo pigments. The other part is a vitamin A sub-product considered to be retinal. There is one for each rod, that combined with retinal types, the rod photo pigment iuiodopsin.

OPSIN: "Arthropods doe not have opsin proteins."
Cite this page: N., Pam M.S., "OPSIN," in PsychologyDictionary.org, April 7, 2013, https://psychologydictionary.org/opsin/ (accessed September 23, 2021).