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. Involved in the behavioral responses ethyl butyrate and to esters in more general. 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. Interacts with Orco, via conserved C-terminal cytoplasmic loops. Complexes exist early in the endomembrane system in olfactory sensory neurons (OSNs), coupling these complexes to the conserved ciliary trafficking pathway. Interacts with snmp1. Expressed with Orco in 17-20 sensory neurons on the medial-proximal edge of the antenna. Expressed in the ab3A neuron which responds to ethyl butyrate. 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. Or2a subfamily.