Proteome-wide analysis of arginine monomethylation reveals widespread occurrence in human cells

The posttranslational modification of proteins by arginine methylation is functionally important, yet the breadth of this modification is not well characterized. Using high-resolution mass spectrometry, we identified 8030 arginine methylation sites within 3300 human proteins in human embryonic kidney 293 cells, indicating that the occurrence of this modification is comparable to phosphorylation and ubiquitylation. A site-level conservation analysis revealed that arginine methylation sites are less evolutionarily conserved compared to arginines that were not identified as modified by methylation. Through quantitative proteomics and RNA interference to examine arginine methylation stoichiometry, we unexpectedly found that the protein arginine methyltransferase (PRMT) family of arginine methyltransferases catalyzed methylation independently of arginine sequence context. In contrast to the frequency of somatic mutations at arginine methylation sites throughout the proteome, we observed that somatic mutations were common at arginine methylation sites in proteins involved in mRNA splicing. Furthermore, in HeLa and U2OS cells, we found that distinct arginine methyltransferases differentially regulated the functions of the pre-mRNA splicing factor SRSF2 (serine/arginine-rich splicing factor 2) and the RNA transport ribonucleoprotein HNRNPUL1 (heterogeneous nuclear ribonucleoprotein U-like 1). Knocking down PRMT5 impaired the RNA binding function of SRSF2, whereas knocking down PRMT4 ...
Source: Signal Transduction Knowledge Environment - Category: Science Authors: Tags: STKE Research Resources Source Type: news