1. The biological characteristics of PRMTs

Arginine methylation is a process in which the nitrogen atom of arginine in polypeptide is modified by methyl group, which is catalyzed by nine enzymes of PRMTs. PRMTs catalyzes the transfer of a methyl from S-adenosyl methionine (SAM) to the terminal guanidine nitrogen atom of arginine to produce methyl arginine and S-adenosine homocysteine [2].

There are three kinds of methyl amino acids catalyzed by PRMTs, which is monomethyl-arginine (MMA), asymmetric dimethyl-arginine (ADMA) and symmetric dimethyl-arginine (SDMA) respectively [3]. ADMA is formed by connecting two methyl groups to one terminal nitrogen atom, SDMA is formed by connecting one methyl group to each guanidine nitrogen atom at the end and MMA is formed by connecting a single methyl group with a terminal nitrogen atom [4].