Receptor for trace amines, including beta-phenylethylamine (b-PEA), p-tyramine (p-TYR), octopamine and tryptamine, with highest affinity for b-PEA and p-TYR. Unresponsive to classical biogenic amines, such as epinephrine and histamine and only partially activated by dopamine and serotonin. Trace amines are biogenic amines present in very low levels in mammalian tissues. Although some trace amines have clearly defined roles as neurotransmitters in invertebrates, the extent to which they function as true neurotransmitters in vertebrates has remained speculative. Trace amines are likely to be involved in a variety of physiological functions that have yet to be fully understood. The signal transduced by this receptor is mediated by the G(s)-class of G-proteins which activate adenylate cyclase. Widely distributed throughout the brain. Strongly expressed in the mitral cell layer of the olfactory bulb, piriform cortex, the arcuate, motor, and mesencephalic trigeminal nuclei, lateral reticular and hypoglossal nuclei, cerebellar Purkinje cells, and ventral horn of the spinal cord. Moderately expressed in the frontal, entorhinal, and agranular cortices, the ventral pallidum, thalamus, hippocampus, several hypothalamic nuclei, ambiguus, dorsal raphe, and gigantocellular reticular nuclei. Weakly expressed in the septum, basal ganglia, amygdala, myelencephalon, and spinal cord dorsal horn. Particularly interesting is the moderate expression in several monoaminergic cell groups, namely the dorsal raphe, the locus coeruleus, and the ventral tegmental area. Belongs to the G-protein coupled receptor 1 family.