Calcium-dependent phospholipid-binding protein that plays a role in calcium-mediated intracellular processes. Binds phospholipid membranes in a calcium-dependent manner (PubMed:9886090). Plays a role in dendrite formation by melanocytes (By similarity). Interacts (via second C2 domain) with OS9 (via C-terminus); this interaction occurs in a calcium-dependent manner in vitro (PubMed:10403379). May interact with NECAB1 (By similarity). Mainly cytoplasmic in absence of calcium. Associated predominantly with membranes in presence of calcium (PubMed:9886090). Translocates to the cell membrane in a calcium-dependent manner (PubMed:21087455, PubMed:26175110). Colocalized with transferrin in intracellular clathrin-coated membrane vesicles in a calcium-dependent manner (PubMed:21087455). Expressed in the brain (PubMed:9645480). Expressed in pyramidal cells, granule cells, and neurons in the dentate gyrus of the hippocampus and in granule cells of the olfactory bulb (at protein level). Expressed in pyramidal cells of the CA1-CA3 regions, in granule cells of the dentate gyrus, in granule cells of the olfactory bulbs, in the mitral cell layer and in neurons of the cerebral cortex layer II, brainstem and spinal cord (PubMed:9886090). Not detected in glial cells (PubMed:9645480, PubMed:9886090). Up-regulated by long-term potentiation (PubMed:9645480). Up-regulated by kainate in an NMDA-type glutamate receptor-dependent manner (PubMed:9645480). The C2 domain 1 binds phospholipids in a calcium-independent manner and is not necessary for calcium-mediated translocation and association to the plasma membrane (PubMed:9886090, PubMed:26175110). The C2 domain 2 binds phospholipids in a calcium-dependent manner and is necessary for calcium-mediated translocation and association to the plasma membrane (PubMed:9886090, PubMed:26175110). The linker region contributes to the calcium-dependent translocation and association to the plasma membrane (PubMed:21087455, PubMed:26175110). The VWFA domain is necessary for association with intracellular clathrin-coated vesicles in a calcium-dependent manner (PubMed:21087455). Belongs to the copine family.