Identification of substrate candidate of protein arginine methyltransferase 3

Abstract

Arginine methylation is a common post-translation modification found in many proteins. Protein-arginine methylatransferase I(PRMT1) contributes >90% of type I protein-arginine methyltransferase activity in cells and tissues and the remnant 10% is done by other PRMT families. To search for the uncovered effect conferred by protein arginine methylation, we purified a 31kDa protein which was coimmunoprecipitated with PRMT3 specifically, and identified it by mass spectroscopy. The protein was identified as 40S RPS2 which constitutes 40S ribosomal protein and participates in mRNA translation fidelity control. The specific binding of RPS2 to PRMT3 was confirmed by GST pulldown experiment in vivo, while in vitro experiment didn’t provide satisfactory confirmation due to the factors affecting the result, which were caused by the difference between eukaryotic and prokaryotic cellular environment. The expression level of RPS2 was increased by cotransfecting with PRMT3, exclusively. The dependence of binding of RPS2 and PRMT3 on methylation and the subject of RPS2 methylation is to be uncovered.