Calcium-dependent phospholipid-binding protein that plays a role in calcium-mediated intracellular processes. Exhibits calcium-dependent cell membrane binding properties (PubMed:21087455, PubMed:26175110). Binds 3 Ca(2+) ions per C2 domain. Translocates to the cell membrane and the nucleus in a calcium-dependent manner (PubMed:21087455, PubMed:26175110). Colocalizes with CD2 at the cell membrane (PubMed:21087455). The C2 domain 2, but not the C2 domain 1, is necessary for calcium-mediated membrane association (PubMed:21087455, PubMed:26175110). The linker region is necessary for calcium-dependent cell membrane association (PubMed:21087455). Belongs to the copine family.