[Zallen JA] ky123 recessive, homozygotes exhibit aberrant anterior position of nerve ring, many ring axons misrouted, ventral nerve cord neurons often misrouted, cross midline. Encodes three isoforms, longest 1273 aa with 5 Ig repeats, 3 FNIII repeats, TM domain, large cytoplasmic domain. ky123 deletes signal sequence and first exon, probable null. Predicted gene ZK377.3 + ZK377.2
sax-3 encodes, by alternative splicing, two isoforms of an ortholog of Drosophila ROUNDABOUT, ROBO3, and LEAK, and of human ROBO1, ROBO2 (OMIM:602431, mutated in vesicoureteral reflux), and ROBO3 (OMIM:608630, mutated in horizontal gaze palsy with progressive scoliosis); in larval hermaphrodites, SAX-3 is required to confine migrating sex myoblasts to the ventral muscle quadrants during their migration through the body and for multiple aspects of sensory, motor, and interneuron axon guidance.
Enables axon guidance receptor activity. Involved in generation of neurons and regulation of sensory neuron axon guidance. Located in plasma membrane. Expressed in several structures, including QR.a; QR.p; body wall musculature; neuroblasts; and neurons. Human ortholog(s) of this gene implicated in several diseases, including autosomal recessive congenital nystagmus; hematologic cancer (multiple); and myositis (multiple). Is an ortholog of human ROBO1 (roundabout guidance receptor 1); ROBO2 (roundabout guidance receptor 2); and ROBO3 (roundabout guidance receptor 3).