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Literature summary for 3.6.1.74 extracted from
- Isolation and characterization of the Candida albicans gene for mRNA 5'-triphosphatase Association of mRNA 5-triphosphatase and mRNA 5-guanylyltransferase activities is essential for the function of mRNA 5-capping enzyme in vivo (1998), FEBS Lett., 435, 49-54 .
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| gene CET1, DNA and amino acid sequence determination and analysis, sequence comparison, functional expression as GST-tagged enzyme in a CET1-deficient Saccharomyces cerevisiae strain under control of the ADH1 promoter. Complementation of the Saccharomyces cerevisiae ceg1DELTA null mutation by Candida albicans CET1 and interaction of CaCet1p with ScCeg1p | Candida albicans |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| additional information | CaCET1 rescues CET1-deficient Saccharomyces cerevisiae cells when expressed under the control of the ADH1 promoter, whereas the human capping enzyme derivatives that are active for TPase activity but defective in mRNA 5'-guanylyltransferase (GTase) activity do not. Yeast two-hybrid analysis reveals that Candida albicans Cet1p can bind to the Saccharomyces cerevisiae GTase in addition to its endogenous partner, the Candida albicans GTase. In contrast, neither the full-length human capping enzyme nor its TPase domain interact with the yeast GTase. The failure of the human TPase activity to complement an Saccharomyces cerevisiae cet1DELTA null mutation is attributable, at least in part, to the inability of the human capping enzyme to associate with the yeast GTase, and the physical association of GTase and TPase is essential for the function of the capping enzyme in vivo. Complementation of an Saccharomyces cerevisiae ceg1DELTA null mutation by Candida albicans CET1 and interaction of CaCet1p with ScCeg1p (alpha-subunit with mRNA 5'-guanylyltransferase (GTase) activity) | Candida albicans |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| a 5'-triphospho-[mRNA] + H2O | Homo sapiens | - |
a 5'-diphospho-[mRNA] + phosphate | - |
? |  |
| a 5'-triphospho-[mRNA] + H2O | Candida albicans | - |
a 5'-diphospho-[mRNA] + phosphate | - |
? | |
| a 5'-triphospho-[mRNA] + H2O | Candida albicans ATCC MYA-2876 | - |
a 5'-diphospho-[mRNA] + phosphate | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Candida albicans | O93803 | - |
- |
| Candida albicans ATCC MYA-2876 | O93803 | - |
- |
| Homo sapiens | O60942 | - |
- |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| recombinant GST-tagged Cet1p from CET1-deficient Saccharomyces cerevisiae strain by glutathione affinity chromatography | Candida albicans |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| a 5'-triphospho-[mRNA] + H2O | - |
Homo sapiens | a 5'-diphospho-[mRNA] + phosphate | - |
? | |
| a 5'-triphospho-[mRNA] + H2O | - |
Candida albicans | a 5'-diphospho-[mRNA] + phosphate | - |
? | |
| a 5'-triphospho-[mRNA] + H2O | [gamma-32P]ATP-terminated RNA | Homo sapiens | a 5'-diphospho-[mRNA] + phosphate | - |
? | |
| a 5'-triphospho-[mRNA] + H2O | [gamma-32P]ATP-terminated RNA | Candida albicans | a 5'-diphospho-[mRNA] + phosphate | - |
? | |
| a 5'-triphospho-[mRNA] + H2O | - |
Candida albicans ATCC MYA-2876 | a 5'-diphospho-[mRNA] + phosphate | - |
? | |
| a 5'-triphospho-[mRNA] + H2O | [gamma-32P]ATP-terminated RNA | Candida albicans ATCC MYA-2876 | a 5'-diphospho-[mRNA] + phosphate | - |
? | |
| additional information | cap formation by the eukaryotic GTase (EC 2.7.7.50) requires an RNA with a 5'-diphosphate end as the substrate | Candida albicans | ? | - |
- |
|
| additional information | cap formation by the eukaryotic GTase (EC 2.7.7.50) requires an RNA with a 5'-diphosphate end as the substrate. Inability of the human capping enzyme to bind to the yeast GTase | Homo sapiens | ? | - |
- |
|
| additional information | cap formation by the eukaryotic GTase (EC 2.7.7.50) requires an RNA with a 5'-diphosphate end as the substrate | Candida albicans ATCC MYA-2876 | ? | - |
- |
|
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| CaCET1 | - |
Candida albicans |
| CaCet1p | - |
Candida albicans |
| HCE1 | - |
Homo sapiens |
| HCE1A | - |
Homo sapiens |
| HCE1B | - |
Homo sapiens |
| More | cf. EC 2.7.7.50 | Homo sapiens |
| mRNA 5'-capping enzyme triphosphatase 1 | - |
Homo sapiens |
| mRNA 5'-capping enzyme triphosphatase 1 | - |
Candida albicans |
| mRNA 5'-triphosphatase | - |
Homo sapiens |
| mRNA 5'-triphosphatase | - |
Candida albicans |
| Tpase | - |
Homo sapiens |
| Tpase | - |
Candida albicans |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 30 | - |
assay at | Homo sapiens |
| 30 | - |
assay at | Candida albicans |
pH Optimum
| pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|
| 7.9 | - |
assay at | Homo sapiens |
| 7.9 | - |
assay at | Candida albicans |
General Information
| General Information | Comment | Organism |
|---|---|---|
| malfunction | HCE1A and HCE1B have been identified as variants of HCE1. Hce1p possesses both TPase and GTase activities, but Hce1a and Hce1b proteins have deletions within the ORF and lack GTase activity. The failure of Hce1a and Hce1b proteins to complement an Saccharomyces cerevisiae cet1DELTA null mutation may be due to the failure of complex formation between the yeast GTase and the human capping enzyme | Homo sapiens |
| metabolism | during transcription by RNA polymerase II, a cap structure is formed on the 5'-termini of most nascent nuclear pre-mRNAs. Capping of mRNA has been shown to be important for the stabilization, processing, nuclear export, and efficient translation of mRNA. Capping involves at least three enzymes called mRNA 5'-triphosphatase (TPase), mRNA 5'-guanylyltransferase (GTase), and cap methyltransferase (MTase). TPase converts the 5'-triphosphate end of a nascent RNA chain into a diphosphate end, and GTase transfers the GMP moiety of GTP to the newly produced 5'-diphosphate end of RNA to form a blocking structure. Thereafter, MTase attaches a methyl group to the 7 position of the terminal guanosine of RNA. As GTase and TPase are essential for the synthesis of the core cap structure, they are called mRNA 5'-capping enzymes. The physical association of mRNA 5'-guanylyltransferase (GTase) and mRNA 5'-triphosphatase (TPase) is essential for the function of the capping enzyme in vivo | Candida albicans |
| additional information | neither the full-length human capping enzyme nor its TPase domain interact with the yeast GTase. The failure of the human TPase activity to complement an Saccharomyces cerevisiae cet1DELTA null mutation is attributable, at least in part, to the inability of the human capping enzyme to associate with the yeast GTase, and the physical association of GTase and TPase is essential for the function of the capping enzyme in vivo | Homo sapiens |
| physiological function | during transcription by RNA polymerase II, a cap structure is formed on the 5'-termini of most nascent nuclear pre-mRNAs. Capping of mRNA has been shown to be important for the stabilization, processing, nuclear export, and efficient translation of mRNA. Capping involves at least three enzymes called mRNA 5'-triphosphatase (TPase), mRNA 5'-guanylyltransferase (GTase), and cap methyltransferase (MTase). TPase converts the 5'-triphosphate end of a nascent RNA chain into a diphosphate end, and GTase transfers the GMP moiety of GTP to the newly produced 5'-diphosphate end of RNA to form a blocking structure. Thereafter, MTase attaches a methyl group to the 7 position of the terminal guanosine of RNA. As GTase and TPase are essential for the synthesis of the core cap structure, they are called mRNA 5'-capping enzymes. The physical association of mRNA 5'-guanylyltransferase (GTase) and mRNA 5'-triphosphatase (TPase) is essential for the function of the capping enzyme in vivo | Candida albicans |
| physiological function | during transcription by RNA polymerase II, a cap structure is formed on the 5'-termini of most nascent nuclear pre-mRNAs. Capping of mRNA has been shown to be important for the stabilization, processing, nuclear export, and efficient translation of mRNA. Capping involves at least three enzymes called mRNA 5'-triphosphatase (TPase), mRNA 5'-guanylyltransferase (GTase), and cap methyltransferase (MTase). TPase converts the 5'-triphosphate end of a nascent RNA chain into a diphosphate end, and GTase transfers the GMP moiety of GTP to the newly produced 5'-diphosphate end of RNA to form a blocking structure. Thereafter, MTase attaches a methyl group to the 7 position of the terminal guanosine of RNA. As GTase and TPase are essential for the synthesis of the core cap structure, they are called mRNA 5'-capping enzymes. The physical association of mRNA 5'-guanylyltransferase (GTase) and mRNA 5'-triphosphatase (TPase) is essential for the function of the capping enzyme in vivo. In humans, GTase and TPase activities always reside in one enzyme, HCE1 | Homo sapiens |
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