Enables cell-cell adhesion mediator activity. Acts upstream of or within dendrite development; homophilic cell adhesion via plasma membrane adhesion molecules; and regulation of synapse organization. Located in axon; dendrite; and inhibitory synapse. Is expressed in several structures, including alimentary system; central nervous system; limb; sensory organ; and urinary system. Orthologous to human IGSF9 (immunoglobulin superfamily member 9). [provided by Alliance of Genome Resources, Apr 2022]