Roundabout controls axon crossing of the CNS midline and defines a novel subfamily of evolutionarily conserved guidance receptors

Cell. 1998 Jan 23;92(2):205-15. doi: 10.1016/s0092-8674(00)80915-0.


The robo gene in Drosophila was identified in a large-scale mutant screen for genes that control the decision by axons to cross the CNS midline. In robo mutants, too many axons cross and recross the midline. Here we show that robo encodes an axon guidance receptor that defines a novel subfamily of immunoglobulin superfamily proteins that is highly conserved from fruit flies to mammals. For those axons that never cross the midline, Robo is expressed on their growth cones from the outset; for the majority of axons that do cross the midline, Robo is expressed at high levels on their growth cones only after they cross the midline. Transgenic rescue experiments reveal that Robo can function in a cell-autonomous fashion. Robo appears to function as the gatekeeper controlling midline crossing.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Animals, Genetically Modified
  • Axons / physiology*
  • Central Nervous System / embryology
  • Chromosome Walking
  • Cloning, Molecular
  • Conserved Sequence / genetics*
  • Drosophila / embryology*
  • Drosophila / genetics
  • Gene Expression Regulation, Developmental
  • Genes, Insect / genetics
  • Immunoglobulins / genetics
  • Molecular Sequence Data
  • Nerve Tissue Proteins
  • Polymorphism, Restriction Fragment Length
  • RNA, Messenger / analysis
  • Rats
  • Receptors, Immunologic / analysis
  • Receptors, Immunologic / chemistry
  • Receptors, Immunologic / genetics*
  • Roundabout Proteins
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid


  • Immunoglobulins
  • Nerve Tissue Proteins
  • RNA, Messenger
  • Receptors, Immunologic

Associated data

  • GENBANK/AF040989
  • GENBANK/AF040990
  • GENBANK/AF040991
  • GENBANK/AF041082