Acts upstream of or within positive regulation of synapse assembly. Predicted to be located in membrane. Predicted to be integral component of membrane. Predicted to be active in extracellular matrix and extracellular space. Is expressed in several structures, including central nervous system and nasal pit. Orthologous to human LINGO4 (leucine rich repeat and Ig domain containing 4). [provided by Alliance of Genome Resources, Apr 2022]