Each ORCO monomer of 478 amino acids has 7 membrane-spanning α-helices connected by intracellular amino-and extracellular carboxy-terminal loops , which are intracellularly anchored by densely packet α-helices ( ~ 70 % of monomer contacts). The activation of monomers induces ion flow and OR odor detection. Anti-ORCO ligands reduce or block the ion flow through conformational changes affecting their central channel to interfere with OR odor detection.