A new study published in Proteomics explored the methylated sites in three species E. coli S. cerevisiae and HeLa cells. Here a total of 234 methylated sites on 187 proteins with high localization confidence including 94 unreported methylated sites on 9 different amino acid residues were identified. The findings showed that the pathways enriched with methylated proteins were mainly involved in central metabolism for E. coli and S. cerevisiae but related to spliceosome for HeLa cells. Further the analysis of methylation preference on different amino acids were conducted in three species. It was noted that protein N terminal methylation was dominant in E. coli while lysine and arginine methylation were widely identified in S. cerevisiae and HeLa cells respectively. Furthermore glutamate methylation sites were found to have statistical significant potential roles in diabetes and obesity. It was stated that these findings expanded the methylome database from microbes to mammals providing a better understanding of protein methylation and its possible functions on disease.