Hydrolysis of the 5'-end of the nascent transcript by the capping enzyme

Stable Identifier
Reaction [transition]
Homo sapiens
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After the capping complex is formed, the RNA triphosphatase activity of the capping enzyme hydrolyzes the 5'-end phosphate group of the nascent mRNA transcript to a diphosphate.
The RNA triphosphatase (RTP) domain of mammalian capping enzyme is a member of a superfamily of phosphatases that include the protein tyrosine phosphatases, some lipid phosphatases, and several nucleic acid phosphatases. This family uses a conserved nucleophilic cysteine residue to attack the target phosphate. A transient phospho-cysteinyl enzyme intermediate is then hydrolyzed to regenerate the enzyme active site. It should be noted that while higher eukaryotic capping enzymes use PTP-like triphosphatase domains, the yeast triphosphatases are a completely different class of enzymes. The yeast RTPs are metal-dependent phosphatases. RNA 5'-triphosphatase (RTP) catalyzed first reaction can be represented as:pppN(pN)n + GTP -> ppN(pN)n + Pi; (n=20-25)

Literature References
PubMed ID Title Journal Year
9512541 Isolation and characterization of a human cDNA for mRNA 5'-capping enzyme.

Yamada-Okabe, H, Shimmi, O, Arisawa, M, Yamada-Okabe, T, Doi, R

Nucleic Acids Res 1998
Catalyst Activity

polynucleotide 5'-phosphatase activity of Capping complex (initial) [nucleoplasm]

Orthologous Events
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