Figure 1.

Types of PTMs accessed by chemical biology approaches. Chemical structures of the modified amino acids are shown. 1, phospho-Ser; 2, phospho-Tyr; 3, sulfo-Tyr; 4, nitro-Tyr; 5, monomethyl-Lys; 6, dimethyl-Lys; 7, trimethyl-Lys; 8, formyl-Lys; 9, acetyl-Lys; 10, propionyl-Lys; 11, butyryl-Lys; 12, crotonyl-Lys; 13, succinyl-Lys; 14, monomethyl-Arg; 15, dimethyl-Arg; 16, O-GlcNAc mimic; 17, O-GlcNAc homo-Ser; 18, N-GlcNAc mimic; 19, mono Ub; 20, di Ub; 21, homotypic Ub chain; 22, mixed Ub chain; 23, branched Ub chain.