G-protein coupled receptor which selectively activates G proteins via ultraviolet A (UVA) light-mediated activation in the skin (PubMed:30284927). Binds both 11-cis retinal and all-trans retinal (By similarity). Regulates melanogenesis in melanocytes via inhibition of alpha-MSH-induced MC1R-mediated cAMP signaling, modulation of calcium flux, regulation of CAMK2 phosphorylation, and subsequently phosphorylation of CREB, p38, ERK and MITF in response to blue light (By similarity). Plays a role in melanocyte survival through regulation of intracellular calcium levels and subsequent BCL2/RAF1 signaling (By similarity). Additionally regulates apoptosis via cytochrome c release and subsequent activation of the caspase cascade (By similarity). Required for TYR and DCT blue light-induced complex formation in melanocytes (By similarity). Involved in keratinocyte differentiation in response to blue-light (By similarity). Required for the UVA-mediated induction of calcium and mitogen-activated protein kinase signaling resulting in the expression of MMP1, MMP2, MMP3, MMP9 and TIMP1 in dermal fibroblasts (By similarity). Plays a role in light-mediated glucose uptake, mitochondrial respiration and fatty acid metabolism in brown adipocyte tissues (PubMed:32040503). May be involved in photorelaxation of airway smooth muscle cells, via blue-light dependent GPCR signaling pathways (PubMed:30284927). Interacts with MC1R; the interaction results in a decrease in MC1R-mediated cAMP signaling and ultimately a decrease in melanin production in melanocytes. Expressed in the eye (at protein level) (PubMed:30284927). Expressed in tracheal airway smooth muscle (PubMed:30284927). Expressed in brown adipocyte tissue; expression becomes more abundant during differentiation (PubMed:32040503). Strongly expressed in brain (PubMed:10234000). Highly expressed in the preoptic area and paraventricular nucleus of the hypothalamus (PubMed:10234000). 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 (PubMed:10234000). Expressed at substantial levels in the dorsal pons at 18.5 dpc (PubMed:10234000). Expressed in Purkinje cells at P4, with expression becoming striped at P20 (PubMed:10234000). Expressed in the cerebral cortex from 18.5 dpc with a rostrocaudal gradient of expression becoming evident at P20 (PubMed:10234000). No visible phenotype (PubMed:32040503). Increased weight gain on a high fat diet, as a result of increased fat mass and increased insulin resistance (PubMed:32040503). Increased basal glucose uptake in brown adipocytes, potentially as a result of decreased GLUT1 expression (PubMed:32040503). Significantly reduced lipocytic rate, mitochondrial DNA expression and cytochrome C oxidase activity in brown adipocyte tissues (PubMed:32040503). Loss of light-mediated increase in glucose uptake, mitochondrial respiration, thermogenic capacity and lipid metabolism-related gene expression in brown adipocyte tissues (PubMed:32040503). Impaired maximum thermogenic capacity with reduced heat production and reduced oxygen consumption in response to norepinephrine treatment in brown adipocytes (PubMed:32040503). Belongs to the G-protein coupled receptor 1 family. Opsin subfamily.