Intracellular G protein-coupled receptor for trace amines, which recognizes endogenous amine-containing metabolites such as beta- phenylethylamine (beta-PEA), 3-iodothyronamine (T1AM), isoamylamine (IAA), cadaverine (CAD), cyclohexylamine (CHA), p-tyramine (p-TYR), trimethylamine (TMA), octopamine and tryptamine (PubMed:11459929, PubMed:11723224, PubMed:15718104, PubMed:31399635, PubMed:36100653, PubMed:37935376, PubMed:37935377, PubMed:37963465, PubMed:38168118). Also functions as a receptor for various drugs and psychoactive substances, such as amphetamine and methamphetamine (PubMed:31399635, PubMed:37935376, PubMed:37935377). Unresponsive to classical biogenic amines, such as epinephrine and histamine and only partially activated by dopamine and serotonin (PubMed:11459929, PubMed:11723224). Expressed in both the central and peripheral nervous system: TAAR1 activation regulates the activity of several neurotransmitter signaling pathways by (1) decreasing the basal firing rates of the neurons involved and by (2) lowering the sensitivity of receptors to neurotransmitters (PubMed:37935376, PubMed:37935377, PubMed:37963465, PubMed:38168118). Ligand binding causes a conformation change that triggers signaling via guanine nucleotide-binding proteins (G proteins) and modulates the activity of downstream effectors (PubMed:31399635, PubMed:37935376, PubMed:37963465). TAAR1 is coupled with different G(i)/G(o)-, G(s)- or G(q)/G(11) classes of G alpha proteins depending on the ligand (PubMed:31399635, PubMed:37935376, PubMed:37963465). CAD-binding is coupled to G(i)/G(o) G alpha proteins and mediates inhibition of adenylate cyclase activity (PubMed:37935376, PubMed:37963465). T1AM- or beta-PEA-binding is coupled to G(s) G alpha proteins and mediates activation of adenylate cyclase activity (PubMed:37935376, PubMed:37963465). CHA- or IAA-binding is coupled to G(q)/G(11) G alpha proteins and activates phospholipase C-beta, releasing diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3) second messengers (PubMed:37935376, PubMed:37963465). TMA-binding is coupled with all three G(i)/G(o)-, G(s)- or G(q)/G(11) G alpha protein subtypes (PubMed:37935376, PubMed:37963465). Amphetamine-binding is coupled with G(s)- or G(12)/G(13) G alpha protein subtypes (PubMed:31399635). {ECO:0000269|PubMed:11459929, ECO:0000269|PubMed:11723224, ECO:0000269|PubMed:15718104, ECO:0000269|PubMed:31399635, ECO:0000269|PubMed:36100653, ECO:0000269|PubMed:37935376, ECO:0000269|PubMed:37935377, ECO:0000269|PubMed:37963465, ECO:0000269|PubMed:38168118}. This is the function of ENSG00000146399 (TAAR1, trace amine associated receptor 1).