Transcription factor essential for the identity of ASE chemosensory neurons. Acts by activating expression of genes that are specific for ASE chemosensory neurons, such as seven-transmembrane receptors or guanylate cyclase. Also required to control the left/right asymmetry in ASE chemosensory neurons by regulating expression of genes such as cog-1 and ceh-36. Expressed in ASE chemosensory neurons and in some other neurons.