Binding Site for Robo Receptors Revealed by Dissection of the Leucine-Rich Repeat Region of Slit.
Howitt, J.A., Clout, N.J., Hohenester, E.(2004) EMBO J 23: 4406
- PubMed: 15496984 
- DOI: https://doi.org/10.1038/sj.emboj.7600446
- Primary Citation of Related Structures:  
1W8A - PubMed Abstract: 
Recognition of the large secreted protein Slit by receptors of the Robo family provides fundamental signals in axon guidance and other developmental processes. In Drosophila, Slit-Robo signalling regulates midline crossing and the lateral position of longitudinal axon tracts. We report the functional dissection of Drosophila Slit, using structure analysis, site-directed mutagenesis and in vitro assays. The N-terminal region of Slit consists of a tandem array of four independently folded leucine-rich repeat (LRR) domains, connected by disulphide-tethered linkers. All three Drosophila Robos were found to compete for a single highly conserved site on the concave face of the second LRR domain of Slit. We also found that this domain is sufficient for biological activity in a chemotaxis assay. Other Slit activities may require Slit dimerisation mediated by the fourth LRR domain. Our results show that a small portion of Slit is able to induce Robo signalling and indicate that the distinct functions of Drosophila Robos are encoded in their divergent cytosolic domains.
Organizational Affiliation: 
Department of Biological Sciences, Imperial College London, London, UK. e.hohenester@imperial.ac.uk