Receptor for netrin required for motor axon guidance. Mediates both short- and long-range axon motor repulsion in the developing nervous system upon ligand binding. Also involved in glial migration. While short-range repulsion requires both fra and unc-5, long-range repulsion only requires unc-5. Prior to gastrulation, it is strongly expressed in the presumptive mesoderm. Mesodermal expression begins to fade during stages 13-14, persisting only in the cells that form the dorsal vessel. Expressed within the CNS from late stage 13, shortly after the first axons have extended. Detected in several dispersed clusters of cells within the CNS, increasing in number as development proceeds. Also expressed in the peripheral and exit glia, which migrate laterally out of the CNS between stages 14 and 17. Strongly expressed in motor axons that exit the CNS ipsilaterally via the segmental nerve root (SN). Not expressed on either commissural or longitudinal axons within the CNS, nor on motor axons that exit via the intersegmental nerve (ISN). In the periphery, it is detected on all branches of the SN. Also expressed at high level in exit and peripheral glia along both the SN and ISN. Phosphorylated on different cytoplasmic tyrosine residues. Belongs to the unc-5 family.