Direct mass-spectrometric identification of Arg296 and Arg299 as the methylation sites of hnRNP K protein for methyltransferase PRMT1.
Protein methylation is one of the most important post-translational modifications that contribute to the diversity and complexity of proteome. Here we report the study of in vitro methylation of heterogeneous nuclear ribonucleoprotein K (hnRNP K) with protein arginine methyltransferase 1 (PRMT1), as an enzyme, and S-adenosyl-L-methionine (SAM), as a methyl donor. The mass analysis of tryptic peptides of hnRNP K before and after methylation reveals the addition of four methyl groups in the residues 288-303. Tandem mass-spectrometric analysis of this peptide shows that both Arg296 and Arg299 are dimethylated. In addition, fragmentation analysis of such methylated arginines illustrate that they are both asymmetric dimethylarginines. Since Arg296 and Arg299 are located near the SH3-binding domains of hnRNP K, such methylation has the potential in regulating the interaction of hnRNP K with Src protein family. Our results provide crucial information for further functional study of hnRNP K methylation.
Chiou
Yi-Ying
YY
Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan.
Lin
Wey-Jinq
WJ
Fu
Shu-Ling
SL
Lin
Chao-Hsiung
CH
D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry* / Q000378:metabolism*; D034641:Heterogeneous-Nuclear Ribonucleoprotein K / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008745:Methylation; D008969:Molecular Sequence Data; D011484:Protein-Arginine N-Methyltransferases / Q000737:chemistry* / Q000378:metabolism*; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry
D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D012097:Repressor Proteins; D001120:Arginine; C099988:PRMT1 protein, human; D011484:Protein-Arginine N-Methyltransferases