Transcription factor. Specifies differentiation of the set of six touch receptor neurons (TRNs). May positively modulate expression of both its own gene and also of homeobox ARX homolog alr-1 in TRNs, forming a positive feedback loop with alr-1, thereby restricting the variability of expression of mec-3. Required to determine the identity of ALM sensory neurons, acting by interacting with unc-86, thereby preventing unc-86 cooperating with pag-3 to induce BDU-neuron specific genes. Binds cooperatively as a heterodimer with unc-86 to sites in the mec-3 gene promoter. Promotes outgrowth of lateral dendritic branches on the PVD nociceptive neurons, probably acting both directly, and upstream of zinc finger protein egl-46