Opsins are members of the guanine nucleotide-binding protein (G protein)-coupled receptor superfamily. In addition to the visual opsins, mammals possess several photoreceptive non-visual opsins that are expressed in extraocular tissues. This gene, opsin 3, is strongly expressed in brain and testis and weakly expressed in liver, placenta, heart, lung, skeletal muscle, kidney, and pancreas. The gene may also be expressed in the retina. The protein has the canonical features of a photoreceptive opsin protein. FUNCTION: May play a role in encephalic photoreception. SUBCELLULAR LOCATION: Membrane; Multi-pass membrane protein. TISSUE SPECIFICITY: Strongly expressed in brain. Highly expressed in the preoptic area and paraventricular nucleus of the hypothalamus. Shows highly patterned expression in other regions of the brain, being enriched in selected regions of the cerebral cortex, cerebellar Purkinje cells, a subset of striatal neurons, selected thalamic nuclei, and a subset of interneurons in the ventral horn of the spinal cord. Also known as: Opsin-3, encephalopsin, panopsin, OPN3, ECPN, opsin 3.