Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
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The presence of adenosine triphosphate, guanosine triphosphate, cytosine triphosphate, or uridine triphosphate reduced the rate of inactivation of vaccinia when heated at 50 C. The virus-associated nucleoside triphosphate phosphohydrolases (adenosine triphosphatase, guanosine triphosphatase, cytosine triphosphatase, and uridine triphosphatase) and ribonucleic acid polymerase were also protected from heat inactivation by these compounds. These obervations are best explained by postulating that ribonucleoside triphosphates bind to enzymes in the virus particle, and that these enzyme-substrate complexes are more resistant to thermal denaturation than are the enzymes without their substrates. The kinetics of heat inactivation of the vaccinia ATP phosphohydrolase activity is biphasic, suggesting that there are two proteins in the vaccinia particle that have this enzyme activity but they have different kinetics of heat inactivation. Any of the vaccinia-associated nucleotide phosphohydrolase activities are protected from heat inactivation by the presence of any one of the respective nucleoside triphosphates. This observation suggests that there is a single enzymatic site in vaccinia that is able to react with any ribonucleoside triphosphate.
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PMID:Protection of vaccinia from heat inactivation by nucleotide triphosphates. 431 59

We have identified cDNAs encoding three isoforms (a1, a2, and a3) of the 100-kDa a subunit of the mouse vacuolar proton-translocating ATPase (V-ATPase). The predicted protein sequences of the three isoforms are 838, 856, and 834 amino acids, respectively, and they display approximately 50% identity between isoforms. Northern blot analysis demonstrated that all three isoforms are expressed in most tissues examined. However, the a1 isoform is expressed most heavily in brain and heart, a2 in liver and kidney, and a3 in liver, lung, heart, brain, spleen, and kidney. We also identified multiple alternatively spliced variants for each isoform. Reverse transcriptase-mediated polymerase chain reaction revealed that one splicing variant of the a1 isoform (a1-I) was expressed only in brain, whereas two other variants (a1-II and a1-III) were expressed in tissues other than brain. These alternatively spliced forms differ in the presence or absence of 6-7 amino acid residues near the amino and carboxyl termini of the proteins encoded. The a3 isoform is also encoded by three alternatively spliced variants, two of which are predicted to encode a protein that is truncated near the border of the amino- and carboxyl-terminal domains of the a subunit and therefore lacks the integral transmembrane-spanning helices thought to participate in proton translocation. Expression of each isoform (with the exception of a1-I) was detectable at all developmental stages investigated, with a1-I absent only in day 7 embryos. The results obtained suggest that isoforms of the 100-kDa a subunit may contribute to tissue-specific functions of the V-ATPase.
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PMID:Molecular cloning and expression of three isoforms of the 100-kDa a subunit of the mouse vacuolar proton-translocating ATPase. 1070 41