mRNA capping enzyme, bifunctional <p>This entry represents bifunctional mRNA-capping enzymes that exhibit RNA 5'-triphosphatase activity (<db_xref db="EC" dbkey="3.1.3.33"/>) in the N-terminal region and mRNA guanylyltransferase activity (<db_xref db="EC" dbkey="2.7.7.50"/>) in the C-terminal region. These enzymes catalyse the first two steps of cap formation via the following steps:</p><p> <ul><li>Removing the gamma-phosphate from the 5'-triphosphate end of nascent mRNA to yield a diphosphate end.</li><li>Followed by the transfer of the gmp moiety of GTP to the 5'-diphosphate terminus.</li></ul> </p>