Required for permeability of amphid and phasmid neurons to external dyes, chemotaxis to ammonium chloride, avoidance of high osmotic stimuli, male mating and dauer formation (PubMed:7705621). Along with dex-1, enables neurite growth and maintenance by anchoring amphid dendritic tips during neuron cell body migration in embryonic and larval development (PubMed:19344940, PubMed:34115759). Monomer under reducing conditions. Homodimer under non-reducing conditions. May also form higher order oligomers. Located at dendritic tips. Secreted following proteolytic cleavage in vitro. In the embryo, expressed in the excretory cell and, during dendrite formation, in the non-neuronal cells surrounding the sensory neurons, including hypodermal cells. Expression is first apparent in bean-stage embryos, peaks in late embryogenesis, reduces in L1 larvae and is negligible in later larval stages and adults. Proteolytically cleaved and secreted in vitro.