Acts as a calcium-dependent, homophilic cell adhesion molecule that regulates neural recognition during the development of the nervous system. Component of the repulsive Plexin signaling response to regulate motor axon guidance at the embryonic stage. Also component of a receptor complex that is required in the adult visual system to innervate the lamina layer; specific targeting of R1-R6 axons (By similarity). Interacts with plexA; component of a receptor complex that mediates the repulsive signaling in response to Semaphorin ligands. Belongs to the protein kinase superfamily. Tyr protein kinase family. Insulin receptor subfamily. The D.melanogaster ortholog of this protein has been proposed to undergo autophosphorylation on tyrosine residues which is induced in response to cell adhesion (PubMed:1371458). However as mammalian orthologs of this protein seem to lack kinase activity this protein may associate with, and be phosphorylated by, an unknown active tyrosine kinase.