The full length SLIT proteins are secreted and, when not bound to ROBO receptors, are indirectly associated with the plasma membrane via the extracellular matrix proteins. These full length SLITs undergo posttranslational modification and proteolytic processing to generate an N-terminal fragment (SLIT2-N) and a corresponding C-terminal fragment (SLIT2-C). SLIT2 is cleaved within the EGF repeats, between EGF5 and EGF6, by unknown proteases. Cleavage of SLIT proteins is evolutionarily conserved, although the molecular biological significance is unknown. The N-terminal fragment of SLIT2 stimulates growth and branching of dorsal root ganglia (DRG) axons, and this activity is opposed by un-cleaved SLIT. The stimulation of axon branching is mediated by ROBO receptors. Additional functional differences between the full-length and N-terminal forms have been discovered in their abilities to repel different populations of axons and dendrites. Finally, SLIT can attract migrating muscles in the fly, and also human endothelial cells, both via ROBO receptors (Brose et al. 1999, Wang et al. 1999).
SLIT C-terminal fragments may transduce signaling independently of ROBO receptors and Neuropilins (semaphorin receptors) by directly binding to Plexin A1 (Delloye-Bourgeois et al. 2015).
Henzel, W, Brose, K, Arnott, D, Goodman, CS, Kidd, T, Wang, KH, Tessier-Lavigne, M
Henzel, W, Brose, K, Bland, KS, Arnott, D, Goodman, CS, Kidd, T, Wang, KH, Tessier-Lavigne, M
peptidase activity of Unidentified protease [cytosol]
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