Semaphorin receptors

Plexins are partners for neuropilins

Science's STKE  05 Oct 1999:
Vol. 1999, Issue 2, pp. tw2
DOI: 10.1126/stke.1999.2.tw2

Membrane-bound and secreted semaphorins regulate a number of cell adhesion processes including axon guidance in the nervous system. However, little is known about the receptors to which they bind. Although neuropilins bind to secreted class 3 semaphorins (Sema3), it is thought that a coreceptor might be required to transduce Sema3 signals because the cytoplasmic tail of neurophilins are short. Tamagnone et al. and Takahashi et al. now demonstrate that plexins, transmembrane proteins with homology in their extracellular domain to semaphorins, bind to neuropilins. Plexins colocalized with neuropilins in developing neural tissue, and inhibition of plexin in cultured neurons inhibited neuropilin-mediated response to exogenous Sema3A. The protein complex exhibited a higher affinity for Sema3A than neuropilin alone. Both groups propose that a plexin-neuropilin protein complex acts as a semaphorin receptor to regulate growth cone collapse. Plexins are also classified according to the type of semaphorin to which they bind.

Takahashi, T., Fournier, A., Nakamura, F., Wang, L-H., Murakami, Y., Kalb, R.G., Fujisawa, H., and Strittmatter, S.M. (1999) Plexin-Neuropilin 1 complexes form functional semaphorin-3A receptors. Cell 99: 59-69. Online Journal

Tamagone, L., Artigiani, S., Chen, H., He, Z., Ming, G-l., Song, H-j., Chedotal, A., Winberg, M.L., Goodman, C.S., Poo, M-m., Tessier-Lavigne, M., and Comoglio, P.M. (1999) Plexins are a large family of receptors for transmembrane, secreted, and GPI-anchored semaphorins in vertebrates. Cell 99: 71-80. Online Journal