Olfactory receptor that is activated by amino acids that act as potent odorants in fish. Most highly activated by basic amino acids such as L-lysine and L-arginine. Homodimer; disulfide-linked. Expressed in olfactory epithelium. Also expressed in gills, tongue, lips and palatal organ. Not expressed in brain, kidney, liver, muscle, intestine, ovary and skin. In olfactory epithelium, it is widely expressed over the apical and medial portions of the olfactory sensory neurons, regions that contain olfactory neurons. Expressed in external epithelia, which contains taste buds and solitary chemosensory cells. On gill rakers, it is widely expressed in the surface epithelium, but excluded from taste buds. N-glycosylated. Belongs to the G-protein coupled receptor 3 family.