Abstract: Many nucleosides in transfer RNAs are modified. Modified nucleosides play important roles in the structure and function of tRNAs. Up to now, more than 108 kinds of modified nucleosides have been identified, and methylation is one of most commonly found post-transcriptional modification on tRNA molecules. Methylation and N1 position of guanosine, or 1-methylguanosine (m1G), is presented on different tRNAs. Studies have shown that the presence of m1G at those locations are good for stabilizing tRNA tertiary structure, correct folding and preventing translational error. In this review, we discussed the location and functionality of m1G, summarized enzymes found for m1G, and compard their biochemical activity and biological roles in different organisms, with highlight on the mechanism difference on the synthesis and difference on substrate recognition by protein domains for each of the activity. we hope to provide a reference for the study of m1G nucleoside modification and its related proteins, and to give insight for future research in related area.

Key words: tRNA, 1-methylguanosine, modified nucleoside, methyltransferase, protein structure and function