Protein lysine methyl transferases

Lysine methylation marks Monoamine oxidase inhibitor Plant homeodomain Posttranslational modification Protein lysine methyl transferase... 

A number of proteins such as histones, cytochrome c and certain flagellar proteins are found to contain methylated amino acids (19). Three different methylases have been characterized and all require S-adenosylmethionine (SAM) as the methyl donor (20-23). Protein methylase I (SAM-protein arginine methyl transferase) methylates the guanidine side chain of arginine residue protein methylase II (SAM-protein carboxyl methyltransferase) transfers methyl groups only to 8- and y-carboxyl groups in the peptide chain. Carboxyl groups in the a position cannot serve as acceptors. Protein methylase III (SAM-protein lysine... 

Methylation. Protein methylation serves several purposes in eukaryotes. The methylation of altered aspartate residues by a specific type of methyltransferase promotes either the repair or the degradation of damaged proteins. Other methyl-transferases catalyze reactions that alter the cellular roles of certain proteins. For example, methylated lysine residues have been found in such disparate proteins as ribulose-2,3-bisphosphate carboxylase, calmodulin, histones, certain ribo-... 

Tuck, M. T., Farooqui, J. Z., Paik, W. K. (1985). Two histone Hl-specific protein-lysine N-methyl-transferases from Euglena gracilis Purification and characterization. J. Biol. Chem. 260, 7114-7121. 

In vitro catalytic data have been obtained for only a few of the characterized SET domain containing proteins. These data are summarized in Fig. 5. Most of the examined HKMTs have optimal methyl transferase activity between a pH of 8 and 10. The mechanism for methyl group attachment to lysine residues is illustrated in Fig. 6. 

Lysine methyltransferases catalyze the transfer of methyl groups from the cosubstrate SAM to certain lysine residues in histone proteins. To characterize modulators of these transferases, the above-mentioned antibody-based assay protocols are also applicable. 

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