Acts as a synaptic organizer in specific subsets of neurons in the brain (By similarity). Essential for long-term maintenance but not establishment of excitatory synapses (By similarity). Homohexamer; disulfide-linked homotrimers. The trimers are assembled via the globular C1q domains. The trimers associate via N-terminal cysteine residues to form disulfide-linked hexamers. May form homooligomers or heterooligomers with CBLN1 and CBLN3 prior to secretion. Once secreted, does not interact with other CBLN family members. Interacts with GRID2, and more weakly with GRID1. Interacts with NRXN1 and NRXN2 long and short isoforms produced by alternative promoter usage. Weakly interacts with NRXN3 short isoform and not at all with NRXN3 long isoform (By similarity). A number of isoforms are produced. Brain (cerebellum), adrenal gland and spleen. In the adrenal gland, expressed at high levels in the zona glomerulosa and at low levels in the zona fasciculata-reticularis.