Adhesion molecule that promotes lamina-specific synaptic connections in the retina and is specifically required for the formation of neuronal circuits that detect motion. Acts by promoting formation of synapses between two specific retinal cell types: the retinal ganglion cells W3B-RGCs and the excitatory amacrine cells VG3-ACs. Formation of synapses between these two cells plays a key role in detection of motion. Promotes synaptic connectivity via homophilic interactions. Homodimer; mediates homophilic interactions to promote cell adhesion. Interacts (via PDZ-binding motif) with MAGI1, MAGI2, DLG2, DLG3 and DLG4. the PDZ-binding motif mediates interaction with PDZ domain-containing proteins MAGI1, MAGI2, DLG2, DLG3 and DLG4 and is required for is required for synaptic localization in photoreceptors. Belongs to the sidekick family. Truncated N-terminus. Discerning change - Issue 176 of February 2016