A highly conserved lysine within the guanylyltransferase (GT) site of the mRNA capping enzyme attacks the alpha-phosphate of GTP. An enzyme-GMP covalent intermediate is formed.
Yamada-Okabe, T, Doi, R, Shimmi, O, Arisawa, M, Yamada-Okabe, H
mRNA guanylyltransferase activity of Capping complex (hydrolyzed) [nucleoplasm]
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