Immunoaffinity Enrichment and Mass Spectrometry Analysis of Protein Methylation

Cell Signaling Technology, United States
Molecular &amp Cellular Proteomics (Impact Factor: 7.25). 10/2013; 13(1). DOI: 10.1074/mcp.O113.027870
Source: PubMed

ABSTRACT Protein methylation is a common posttranslational modification that mostly occurs on arginine and lysine residues. Arginine methylation has been reported to regulate RNA processing, gene transcription, DNA damage repair, protein translocation, and signal transduction. Lysine methylation is best known to regulate histone function and is involved in epigenetic regulation of gene transcription. To better study protein methylation, we have developed highly specific antibodies against monomethyl arginine, asymmetric dimethyl arginine, and monomethyl, dimethyl, and trimethyl lysine motifs respectively. These antibodies were used to perform immunoaffinity purification (IAP) of methyl peptides followed by LC-MS/MS analysis to identify and quantify arginine and lysine methylation sites in several model studies. Overall, we identified over 1000 arginine methylation sites in human cell lines and mouse tissues, and approximately 160 lysine methylation sites in human cell line HCT116. The methylation sites that were identified in this study exceed those found in the literature to date. Detailed analysis of arginine-methylated proteins observed in mouse brain compared to those found in mouse embryo shows tissue-specific distribution of arginine methylation, and extends the type of proteins that are known to be arginine methylated to many new protein types. Many arginine-methylated proteins that we identified from the brain including receptors, ion channels, transporters, and vesicle proteins, are involved in synaptic transmission, while the most abundant methylated proteins identified from mouse embryo are transcriptional regulators and RNA processing proteins.

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