G protein-coupled receptor for 5-hydroxytryptamine (serotonin), a biogenic hormone that functions as a neurotransmitter, a hormone and a mitogen (PubMed:35714614, PubMed:36989299, PubMed:37327704, PubMed:8522988). Also has a high affinity for tricyclic psychotropic drugs (By similarity). Ligand binding causes a conformation change that triggers signaling via guanine nucleotide- binding proteins (G proteins) and modulates the activity of downstream effectors (PubMed:35714614). HTR6 is coupled to G(s) G alpha proteins and mediates activation of adenylate cyclase activity (PubMed:35714614, PubMed:37327704). Controls pyramidal neurons migration during corticogenesis, through the regulation of CDK5 activity (By similarity). Is an activator of mTOR signaling (PubMed:23027611). {ECO:0000250|UniProtKB:P31388, ECO:0000250|UniProtKB:Q9R1C8, ECO:0000269|PubMed:23027611, ECO:0000269|PubMed:35714614, ECO:0000269|PubMed:36989299, ECO:0000269|PubMed:37327704, ECO:0000269|PubMed:8522988}. This is the function of HTR6 (5-hydroxytryptamine receptor 6, Ensembl gene identifier ENSG00000158748).