A capping enzyme (CE) is an enzyme that catalyzes the attachment of the 5' cap to messenger RNA molecules that are in the process of being synthesized in the cell nucleus during the first stages of gene expression. The addition of the cap occurs co-transcriptionally, after the growing RNA molecule contains as little as 25 nucleotides. The enzymatic reaction is catalyzed specifically by the phosphorylated carboxyl-terminal domain (CTD) of RNA polymerase II. The 5' cap is therefore specific to RNAs synthesized by this polymerase rather than those synthesized by RNA polymerase I or RNA polymerase III. Pre-mRNA undergoes a series of modifications - 5' capping, splicing and 3' polyadenylation before becoming mature mRNA that exits the nucleus to be translated into functional proteins and capping of the 5' end is the first of these modifications. Three enzymes, RNA triphosphatase, guanylyltransferase, and methyltransferase are involved in the addition of the methylated 5' cap to the mRNA.
Guanylyl transferases are enzymes that transfer a guanosine mono phosphate group, usually from GTP to another molecule, releasing pyrophosphate. Many eukaryotic guanylyl transferases are capping enzymes that catalyze the formation of the 5' cap in the co-transcriptional modification of messenger RNA. Because the 5' end of the RNA molecule ends in a phosphate group, the bond formed between the RNA and the GTP molecule is an unusual 5'-5' triphosphate linkage, instead of the 3'-5' linkages between the other nucleotides that form an RNA strand. In capping enzymes, a highly conserved lysine residue serves as the catalytic residue that forms a covalent enzyme-GMP complex.
In enzymology, a mRNA (guanine-N7-)-methyltransferase also known as mRNA cap guanine-N7 methyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a mRNA (nucleoside-2'-O-)-methyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a protein-glutamate O-methyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a tRNA (cytosine-5-)-methyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a tRNA (guanine-N1-)-methyltransferase (EC 2.1.1.31) is an enzyme that catalyzes the chemical reaction
In enzymology, a tRNA (guanine-N7-)-methyltransferase (EC 2.1.1.33) is an enzyme that catalyzes the chemical reaction
In enzymology, a RNA-3′-phosphate cyclase is an enzyme that catalyzes the chemical reaction
The enzyme lysophospholipase (EC 3.1.1.5) catalyzes the reaction
The enzyme polynucleotide 5′-phosphatase (RNA 5′-triphosphatase, RTPase, EC 3.1.3.33) is an enzyme that catalyzes the reaction
In enzymology, an ATP phosphoribosyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, an adenosylcobinamide-phosphate guanylyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a fucose-1-phosphate guanylyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a mannose-1-phosphate guanylyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a nucleoside-triphosphate-aldose-1-phosphate nucleotidyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a polynucleotide adenylyltransferase is an enzyme that catalyzes the chemical reaction
Guanine nucleotide-binding protein G(o) subunit alpha is a protein that in humans is encoded by the GNAO1 gene.
Protein farnesyltransferase/geranylgeranyltransferase type-1 subunit alpha is an enzyme that in humans is encoded by the FNTA gene.
tRNA(His) guanylyltransferase is an enzyme with systematic name p-tRNA(His):GTP guanylyltransferase (ATP-hydrolysing). This enzyme catalyses the following chemical reaction
