Odorant receptor which mediates acceptance or avoidance behavior, depending on its substrates. The odorant receptor repertoire encodes a large collection of odor stimuli that vary widely in identity, intensity, and duration. Complexes with Orco to form odorant-sensing units, providing sensitive and prolonged odorant signaling and calcium permeability. They are necessary and sufficient to promote functional reconstitution of odor-evoked signaling in sensory neurons that normally respond only to carbon dioxide. Involved in the behavioral responses to esters. Involved in the behavioral responses to pentyl acetate. Interacts with Orco. Complexes exist early in the endomembrane system in olfactory sensory neurons (OSNs), coupling these complexes to the conserved ciliary trafficking pathway. Expressed with Orco in 40 olfactory receptor neurons in a broad area across the antenna, including both anterior and posterior faces. This expression pattern matches the distribution of the small sensilla basiconica. Expression in the antenna is observed late in antennal development at 93 hours APF. The atypical heteromeric and topological design of the odorant receptors appears to be an insect-specific solution for odor recognition, making the OR/Orco complex an attractive target for the development of highly selective insect repellents to disrupt olfactory-mediated host-seeking behaviors of insect disease vectors. Odor-evoked OR currents are independent of known G-protein-coupled second messenger pathways. Belongs to the insect chemoreceptor superfamily. Heteromeric odorant receptor channel (TC 1.A.69) family. Or1a subfamily.