NSP10, Plays a pivotal role in viral transcription by stimulating both nsp14 3'-5' exoribonuclease and 2'-O-methyltransferase (NSP16) activities. Therefore plays an essential role in viral mRNAs cap methylation. 2'-O-methyltransferase (NSP16) that mediates mRNA cap 2'-O-ribose methylation to the 5'-cap structure of viral mRNAs. N7-methyl guanosine cap is a prerequisite for binding of nsp16. Therefore plays an essential role in viral mRNAs cap methylation which is essential to evade immune system. Nsp10 forms a dodecamer and interacts with nsp14 and nsp16; these interactions enhance nsp14 and nsp16 enzymatic activities.