Protein arginine methyltransferases (PRMTs)mediate the transfer of methyl groups to arginine residues in histone and non-histone proteins. PRMT5 is an important member of PRMTs which symmetrically dimethylates arginine 8 in histone H3 (H3R8) and arginine 3 in histone H4 (H4R3). PRMT5 was reported to inhibit some tumor suppressors in leukemia and lymphoma cells and regulate p53 gene, through affecting the promoter of p53. Through methylation of H4R3, PRMT5 can recruit DNA-methyltransferase 3A (DNMT3A) which regulates gene transcription. All the above suggest that PRMT5 has an important function of suppressing cell apoptosis and is a potential anticancer target. Currently, the enzymatic activities of PRMT5 are not clearly understood. In our study, we improved the protein expression methodology and greatly enhanced the yield and quality of the recombinant PRMT5. In addition, mutagenesis and enzymatic studies implicate an interesting mechanism of PRMT5 activity regulation
