Calcium-dependent phospholipid-binding protein that plays a role in calcium-mediated intracellular processes (PubMed:14674885). Involved in the TNF-alpha receptor signaling pathway in a calcium-dependent manner (PubMed:14674885). Exhibits calcium-dependent phospholipid binding properties (PubMed:9430674, PubMed:19539605). Plays a role in neuronal progenitor cell differentiation; induces neurite outgrowth via a AKT-dependent signaling cascade and calcium-independent manner (PubMed:23263657, PubMed:25450385). May recruit target proteins to the cell membrane in a calcium-dependent manner (PubMed:12522145). May function in membrane trafficking (PubMed:9430674). Involved in TNF-alpha-induced NF-kappa-B transcriptional repression by inducing endoprotease processing of the transcription factor NF-kappa-B p65/RELA subunit (PubMed:18212740). Also induces endoprotease processing of NF-kappa-B p50/NFKB1, p52/NFKB2, RELB and REL (PubMed:18212740). Homodimer; homodimerizes via its C2 domains (PubMed:18212740). Interacts with p65/RELA (via N-terminus); this interaction induces proteolytic cleavage of p65/RELA subunit and inhibition of NF-kappa-B transcriptional activity (PubMed:18212740). Interacts (via VWFA domain) with ACTB, CCDC22, MYCBP2, PPP5C, RDX and UBE2O (PubMed:12522145). Translocates to the cell membrane in a calcium-dependent manner (PubMed:21087455, PubMed:25450385). Expressed in neutrophils (at protein level) (PubMed:12949241). Widely expressed. Expressed in the brain. Expressed in neutrophil precursors from bone marrow and peripheral blood (PubMed:12949241). Up-regulated by the inflammatory cytokine TNF-alpha (PubMed:14674885). Up-regulated during neuronal progenitor cell differentiation (PubMed:23263657). C2 domains are necessary for calcium-dependent cell membrane association. C2 domains are necessary for neuronal progenitor cell differentiation in a calcium-independent manner (PubMed:25450385). Belongs to the copine family.