4 Structure of protein arginine methyltransferases

With genome sequencing nearing completion for the modelorganisms used in biomedical research, there is a rapidly growing appreciation that proteomics (including the study of covalent modification to proteins) and transcriptional regulation will likely dominate the research headlines in the next decade. Protein methylation plays a central role in both of these fields, as several different residues (Arg, Lys, Gln) are methylated in cells and methylation plays a central role in regulating chromatin structure and impacts transcription. In some cases, a single arginine can be mono-, symmetrically di-, or asymmetrically di-methylated, with different functional consequences for each of the three forms. This review summarizes the progress that has been made in structural studies of protein arginine methyltrans-ferases and their related sequence conservations; it also discusses, somewhat speculatively, their mechanisms.