The function of CLSTN2 (calsyntenin 2, ENSG00000158258) is as follows. Postsynaptic adhesion molecule that binds to presynaptic neurexins to mediate synapse formation, and which is involved in learning and memory (By similarity). Promotes synapse development by acting as a cell adhesion molecule at the postsynaptic membrane, which associates with neurexin-alpha at the presynaptic membrane (By similarity). {ECO:0000250|UniProtKB:Q99JH7, ECO:0000250|UniProtKB:Q9ER65}.