Figure 6. Model for the regulation of L1-Ankyrin binding by ephrinB1/EphBs through tyrosine phosphorylation at the FIGQY domain during mouse retinocollicular targeting.
During retinal ganglion cell (RGC) axon targeting in superior colliculus (SC), forward ephrinB1/EphB signaling recruits Src kinase to phosphorylated tyrosine residues 604/610 in the juxtamembrane of mouse EphB2 to induce L1-Y1229 tyrosine phosphorylation, potentially facilitating RGC axon growth and/or branch attraction to future termination zones. Reversible dephosphorylation of L1-Y1229 enables L1 to bind ankyrin through spectrin linkage to the actin cytoskeleton, which may promote adhesion and stabilization of synaptic terminals. Tyrosine Y1176 on L1 is not regulated by ephrinB1/EphB signaling and is dispensible for RGC axon mapping in the SC.