The function of ENSG00000268221 (OPN1MW, opsin 1, medium wave sensitive) is as follows. G protein-coupled photoreceptor that selectively activates G(i) proteins in response to medium-wavelength (green) light, thereby decreasing intracellular cAMP levels (PubMed:2937147, PubMed:6140680, Ref.6). Activation occurs when the opsin-bound cis-retinal chromophore absorbs a photon and isomerizes to all-trans-retinal, inducing a conformational change in the opsin that triggers a G protein-mediated phototransduction cascade (Ref.6). Mediates visual perception of green light in cone photoreceptor cells (PubMed:12051694, PubMed:1302020, PubMed:8666378). {ECO:0000269|PubMed:12051694, ECO:0000269|PubMed:1302020, ECO:0000269|PubMed:2937147, ECO:0000269|PubMed:6140680, ECO:0000269|PubMed:8666378, ECO:0000269|Ref.6}.