A novel transmembrane semaphorin can bind c-src

Florian Eckhardt, Oded Behar, Enzo Calautti, Kazuyoshi Yonezawa, Ikuo Nishimoto, Mark C. Fishman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


The semaphorins/collapsins constitute a family of genes unified by the presence of a 'semaphorin domain' which has been conserved through metazoan evolution. The semaphorin family comprises both secreted and transmembrane molecules and is thought to be made up of ligands for as yet unidentified receptors. The functions are not known, with the exception of those of sema III (also referred as sem D and collapsin 1), D-sema I, and D-sema II, which have been shown to be involved in axonal pathfinding. Here we report the identification of a mouse semaphorin cDNA, termed Sema VIb. Although Sema VIb contains the extracellular semaphorin domain, it lacks the immunoglobulin domain or thrombospondin repeats which are present in other described vertebrate (but not invertebrate) transmembrane semaphorins. During development Sema VIb mRNA is expressed in subregions of the nervous system and is particularly prominent in muscle. In adulthood, Sema VIb mRNA is expressed ubiquitously. The cytoplasmic domain of Sema VIb contains several proline-rich potential SH3 domain binding sites. Using an in vitro binding assay, we show that Sema VIb binds specifically the SH3 domain of the protooncogene c-src. In transfected COS cells Sema VIb coimmunoprecipitates with c-src. These results, along with our evidence that Sema VIb can form dimers, suggests that the semaphorin family not only serves as ligands but may include members, especially those which are transmembrane, which serve as receptors, triggering intracellular signaling via an src-related cascade.

Original languageAmerican English
Pages (from-to)409-419
Number of pages11
JournalMolecular and Cellular Neurosciences
Issue number5-6
StatePublished - 1997
Externally publishedYes

Bibliographical note

Funding Information:
We thank Drs. Sylvie Vincent, Susan Eckhardt, Andreas Meyerhans, Kenta Hara, and Valeria Gagliardini for their support and suggestions, Drs. Jeff Settleman, David Baltimore, and Sara Courtneidge for providing us with the GST-SH3 fusion proteins and the c-src expression vector, and Dr. Nadia Rosenthal for providing us with C2C12 cells. F.E. was supported by a Boehringer Ingelheim fellowship.


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