Receptor for netrin (unc-6) required for axon guidance (PubMed:8332188, PubMed:11454756). Mediates axon repulsion of neuronal growth cones in the developing nervous system upon ligand binding (PubMed:1384987, PubMed:8332188, PubMed:11454756, PubMed:9473333). Axon migration is mediated by the secreted unc-6, which promotes attraction of neurons and axons through binding to the unc-40 receptor, while repulsion requires both unc-5 and unc-40 receptors (PubMed:11454756, PubMed:9473333). Involved in the ventral-dorsal and anterior-posterior migration of distal tip cells along the body, which may be mediated by Wnt receptor mom-5, ced-10/Rac, ced-12/ELMO and mig-2/RhoG (PubMed:10631179, PubMed:26292279, PubMed:17716643). Interacts (via cytoplasmic domain) with src-1 (via SH2 domain and SH3 domain) (PubMed:16024786). Interacts with madd-4 (PubMed:25122090). Interacts with unc-129; the interaction is direct (PubMed:19169249). Expressed in cell bodies and axons of the VNC motor neurons that extend axons to the dorsal midline and within the ventral nerve cord (PubMed:12435363). Expressed in gonadal distal tip cells (DTC) (PubMed:16251208). Phosphorylated on different cytoplasmic tyrosine residues (PubMed:11533026, PubMed:12435363, PubMed:16024786). May be phosphorylated on tyrosine residues by src-1 (PubMed:16024786). Tyrosine phosphorylation is unc-6-dependent (PubMed:11533026). Glycosylated via C-mannosylation by dpy-19 at Trp-305 and Trp-308. Failed distal tip cell migration along the dorsal-ventral axis of the body. RNAi-mediated knockdown in mom-5, ced-10, ced-12 or mig-2 mutant backgrounds suppresses the migratory defect of distal tip cells in the respective single mutants. Belongs to the unc-5 family. In contrast to other members of the family, it lacks a canonical signal sequence; the existence of the signal sequence is therefore unsure.