Scatter-factor receptors , semaphorins

Fig. 7. Schematic representation of the domain organizadon, as well as ligand-, receptor-, and co-receptor-binding preferences of the semaphorins and their neuronal receptors. The individual domains are labeled. PSI, Plexin/Semaphorin//ntegrin domain IPX, /mmunoglobulin-like domain found in Plexins (and Met) and in some Transcription factors CUB, domain homologous to complement-binding factors Clr and Cls FV/VIII, domain homologous to coagulation factor V and VIII (also known as F5/8 type C or discoidin domain) MAM, Meprin/A5/fi domain SP, Sex-Plexin domain. Semaphorins, plexins and scatter-factor receptors (MET) share a common semaphorin domain (black heptagon).

Vertebrate A-Plexins are the signaling subunits for secreted class 3 semaphorins, while other plexins interact with semaphorins from different classes (Fiore and Piischel, 2003). In contrast to SemaSA, which is not able to bind directly to A-Plexins, SemalD and Sema7A directly interact with Plexin-Bl and Plexin-Cl, respectively (Takahashi et al, 1999 Tamagnone et al, 1999). Interestingly, all Plexins contain an extracellular semaphorin domain that is strictly required for their function (Fig. 7). A semaphorin domain is also present in the scatter-factor receptor MET (Tamagnone et al, 1999). 

---