Enables cell adhesion molecule binding activity and protein homodimerization activity. Involved in homophilic cell adhesion via plasma membrane adhesion molecules. Acts upstream of or within several processes, including establishment of mitochondrion localization; sperm mitochondrion organization; and spermatid development. Located in cell-cell contact zone; plasma membrane; and zonula adherens. Is expressed in brain; cochlea; enamel organ; male reproductive system; and primitive collecting duct. Human ortholog(s) of this gene implicated in Alzheimer's disease and multiple sclerosis. Orthologous to human NECTIN2 (nectin cell adhesion molecule 2).