RNA Triphosphatase

RNA 5'Triphosphatase (RTPase) includes the phosphatases that cleave the γ-βphosphoanhydride bond of nascent mRNA molecule and releases the free phosphate group. so they generate diphosphate ended RNA from triphosphate precursor mRNA MRNA molecule which is now a substrate for mRNA guanylyltransferase, which will add the GMP group to make the final cap structure. there are two families of RTPase know so far:
(1)metal dependent family of RTPases. yeast, protozoans and viral RTPases require metal co-factor for their activity. The metal requirement is satisfied by either Mg2+ or Mn2+ in most of the cases. this class of enzymes are also able to hydrolyze free NTPs in the presence of either Mn2+ or Co2+.
(2)metal independent family of RTPases. these enzymes are very much similar to protein tyrosine phosphatase in their structure and mechanism. this family includes the RTPase from mammals, plants and other higher eukaryotes. this class of enzymes structurally and mechanistically differ from metal dependent RTPases. these groups do not require metals for their activity, and some enzymes have been shown to be inactivated in the presence of metal ions.