Figure 2: Comprehensive analysis of arginine methylation in T cells using iMethyl-SILAC for high confidence identification.

(a) Experimental strategy. Isomethionine methyl-SILAC-labelled Jurkat or primary T lymphocytes are combined 1:1 and lysed. Proteins are digested with trypsin, chymotrypsin or GluC. Peptides are desalted and methylated peptides are enriched by immuno-affinity purification using D5A12 or MeR4100 antibodies. Putative methylated peptides are identified by mass spectrometry and matched to methyl-SILAC pairs. (b) All identified methyl-SILAC pairs. MethylQuant was used to quantify the methyl-SILAC pairs for each identified arginine-methylated peptide. Methyl-SILAC pairs with Heavy/Light (H/L) ratios between the 5th and 95th percentiles (dashed lines) were accepted. (c) Significantly overrepresented biological processes and molecular function involving identified arginine-methylated proteins.