Odorant coreceptor which complexes with conventional odorant receptors (ORs) to form odorant-sensing units, providing sensitive and prolonged odorant signaling and calcium permeability. Orco is a universal and integral part of the functional odorant receptor, involved in the dendritic localization of other olfactory receptors. Plays a key role in preferred attraction of females for humans over non-human hosts for blood feeding. Human attraction plays a crucial role in the transmission of dengue and yellow fever by the mosquito. Also required for the response to the insect repellent IR3535; or to N,N-Diethyl-meta-toluamide (DEET), the most widely used insect repellent worldwide. Heterodimer with conventional odorant receptors (ORs). Complexes exist early in the endomembrane system in olfactory sensory neurons (OSNs), coupling these complexes to the conserved ciliary trafficking pathway. Found specifically within most antennal and maxillary palp sensilla, as well as in a subset of proboscis sensilla. Expressed in adult chemosensory tissues and during several stages of development. Impairs both honey and host odor attraction. Leads to DEET insensitivity. 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. The homomeric Orco channel is thought to be a cyclic-nucleotide-gated ion channel that depolarizes the olfactory receptor neuron. While many natural and synthetic odorants have been shown to agonize Orco/Or complexes, only a single direct Orco agonist, VUAA1, has been described. On the contrary, amiloride derivatives block Orco/Or complexes. Belongs to the insect chemoreceptor superfamily. Heteromeric odorant receptor channel (TC 1.A.69) family. Orco subfamily. The senses confused - Issue 161 of June 2014