Coordinator of PRMT5 and differentiation stimulator (also known as COPRS or COPR5) is a histone-binding protein required for histone H4 methyltransferase activity of PRMT5, which targets nuclear and cytoplasmic proteins. COPR5 is specifically required for histone H4 'Arg-3' methylation mediated by PRMT5, but not histone H3 'Arg-8' methylation, suggesting that it modulates the substrate specificity of nuclear PRMT5-containing complexes, atleast towards histones. Recombinant COPR5 binds to the N-terminal of histone H4 and is required to recruit PRMT5 to reconstituted nucleosomes in vitro [].
