Calcium-dependent cell-adhesion protein. May play a role in activity-induced synaptic reorganization underlying long term memory. Could be involved in CDH2 internalization through TAOK2/p38 MAPK pathway. In hippocampal neurons, may play a role in the down-regulation of dendritic spines, maybe through its action on CDH2 endocytosis. The N-terminal extracellular domain forms homophilic interactions; these interactions activate p38 MAPK via TAOK2 and trigger endocytosis. Interacts with CDH2; this interaction may lead to CDH2 cointernalization. Interacts with CDH11. Interacts with TAOK2. Also expressed in the cell bodies of neurons of the hippocampus and cortex. Localized to excitatory, but not with inhibitory, synapses. Enriched in brain relative to peripheral tissues, with low expression in the testis. Expressed in hippocampal neurons (at protein level). At E17, expressed in the auditory circuit, most prominently in the inferior colliculus, and later in the medial geniculate and the auditory cortex at P0. At P0, also expressed in targets of retinal projections, such as the superior colliculus, the suprachiasmatic nucleus, and the ventrolateral geniculate nucleus. At the same stage, detected in selected structures of the limbic circuit, including the anterior limbic thalamic nuclei, the hippocampus, amygdala and habenula. Rapidly and transiently induced by maximal electroconvulsive seizure in the hippocampal granule cells, and modestly induced in the pyramidal cells. Also induced by cAMP. May be the only physiologically relevant isoform.