ABSTRACT
Objective:To investigate the arginine (Arg) sites in splicing factor 2/alternative splicing factor (SF2/ASF) methylated by protein arginine methyltransferase 1 (PRMT1). Methods:Wild-type and Arg93,Arg97,Arg109 mutant SF2/ASF plasmids were constructed,and GST-PRMT1,GST-SF2/ASF and arginine mutant GST-SF2/ASF fusion proteins were induced and purified. Methylation activity of PRMT1 on wild-type or mutant SF2/ASF protein and methylated sites of SF2/ASF were examined by methylation assay. The effect of SF2/ASF methylation on its subcellular localization was analyzed by immunofluorescence assay.Results:PRMT1 induced methylation of SF2/ASF at arginine,and PRMT1 did not methylate SF2/ASF when SF2/ASF was mutant at Arg93,Arg97 or Arg109,with Arg97 mutation showing the most profound inhibitory effect. Methylation of SF2/ASF did not affect its subcellular localization.Conclusion:SF2/ASF is a newly identified substrate of PRMT1; Arg93,Arg97 and Arg 109 are the three methylation sites in SF2/ASF,and Arg97 is the main methylation site. Methylation of SF2/ASF does not affect its subcellular localization.