Structural highlights
Function
[MCE1_MOUSE] Bifunctional mRNA-capping enzyme exhibiting RNA 5'-triphosphatase activity in the N-terminal part and mRNA guanylyltransferase activity in the C-terminal part. Catalyzes the first two steps of cap formation: by removing the gamma-phosphate from the 5'-triphosphate end of nascent mRNA to yield a diphosphate end, and by transferring the gmp moiety of GTP to the 5'-diphosphate terminus.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
The 5' capping of mammalian pre-mRNAs is initiated by RNA triphosphatase, a member of the cysteine phosphatase superfamily. Here we report the 1.65 A crystal structure of mouse RNA triphosphatase, which reveals a deep, positively charged active site pocket that can fit a 5' triphosphate end. Structural, biochemical and mutational results show that despite sharing an HCxxxxxR(S/T) motif, a phosphoenzyme intermediate and a core alpha/beta-fold with other cysteine phosphatases, the mechanism of phosphoanhydride cleavage by mammalian capping enzyme differs from that used by protein phosphatases to hydrolyze phosphomonoesters. The most significant difference is the absence of a carboxylate general acid catalyst in RNA triphosphatase. Residues conserved uniquely among the RNA phosphatase subfamily are important for function in cap formation and are likely to play a role in substrate recognition.
Structure and mechanism of the RNA triphosphatase component of mammalian mRNA capping enzyme.,Changela A, Ho CK, Martins A, Shuman S, Mondragon A EMBO J. 2001 May 15;20(10):2575-86. PMID:11350947[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Changela A, Ho CK, Martins A, Shuman S, Mondragon A. Structure and mechanism of the RNA triphosphatase component of mammalian mRNA capping enzyme. EMBO J. 2001 May 15;20(10):2575-86. PMID:11350947 doi:10.1093/emboj/20.10.2575
