Required for the function of one pair of chemosensory neurons called AWA neurons that are involved in chemotaxis to volatile odorants. Acts in a pathway that specifies olfactory neuronal fate. Regulates the transcription of olfactory signaling molecules such as odr-10 that specify AWA neuron identity and function. Represses the expression in AWA neurons of factors such as str-2 which specify AWC neuron identity. Heterodimer with a partner that confers DNA binding capacity or a nuclear hormone receptor whose DNA binding it inhibits. Expressed predominantly in the AWA neurons. May be expressed at all postembryonic stages. Down-regulated by the cyanotoxin microcystin-LR. Worms are defective in chemotaxis to the volatile odorants diacetyl and pyrazine and weakly defective in chemotaxis to 2,4,5-trimethylthiazole, but respond normally to the odorants benzaldehyde, butanone, and isoamyl alcohol. Belongs to the nuclear hormone receptor family. NR0 subfamily.