Complement Component 1Q Subcomponent-Binding Protein (C1QBP) is a nucleus protein that belongs to the MAM33 family. C1QBP is known to bind to the globular heads of C1q molecules and inhibit C1 activation. Mitochondrial C1QBP is a critical mediator of p14ARF-induced apoptosis. C1QBP functions as a chemotactic factor for immature dendritic cells, and migration is mediated through ligation of both C1QBP and cC1qR/CR. C1QBP overexpression successfully blocks mRNA accumulation from the adenovirus major late transcription unit (MLTU) and stimulates RNA polymerase II carboxy-terminal domain phosphorylation in virus-infected cells.