Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The P-type ATPases (e.g., Na+-K+-ATPase and Ca2+-ATPase) occur widely in living cells of fungi, Protozoa, plants, and animals. These ion pumps show a high degree of divergence in their primary structures but share a limited number of common amino acid residues for their ATP-catalytic function. Particularly, the amino acid sequences for the phosphorylation site (DKTGTLT) and the binding site for ATP (and its analogs; GDGVND) are conserved throughout evolution. Using two degenerate oligonucleotides corresponding to these regions, we applied a polymerase chain reaction (PCR) technique to the search for P-type ATPase isoforms, which will provide a clue to the evolutionary mechanisms of ion pumps in Tetrahymena thermophila. A total of 12 distinct P-type ATPase genes were identified. Sequence comparisons revealed that seven of them can be compiled into a multigene family, which is similar to animal Na+-K+- and H+-K+-ATPase genes. One of them is close to the sarco(endo)plasmic reticulum Ca2+-ATPase gene, and the other four share a significant homology with the gene encoding Plasmodium ATPase-1 whose function is unknown. A Northern blot analysis and reverse transcriptase-PCR demonstrated that all identified genes are expressed, but the expression levels vary widely under different culture conditions. A Southern blot analysis after pulse-field gel electrophoresis showed that all of these genes exist in T. thermophila macronuclei. The Na+-K+- and H+-K+-ATPase gene family has a high multiplicity (at least 10 different genes detected on genomic Southern blot analysis) and is distributed on four different macronuclear chromosomes. On the basis of a calculation with the amino acid sequences of the cloned cytoplasmic loop region (between the phosphorylation and the gamma-[4-(N-2-chloroethyl-N-methylamino)]-benzylamido ATP sites), the genes with >80% identity form a cognate linkage group within the same macronuclei chromosome, whereas the genes with <70% identity are separated in different chromosomes. The phylogenetic analysis showed that this multigene family is the result of a series of gene duplications.
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PMID:Primary structure and evolution of the ATP-binding domains of the P-type ATPases in Tetrahymena thermophila. 912 16

Hypertension leads to impaired contractile function. This study examined the impact of inhibition of sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) by thapsigargin or cyclopiazonic acid (CPA) on cardiac contractile function in ventricular myocytes from Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). Mechanical properties were examined including peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR90), and maximal velocity of shortening/relengthening (+/-dL/dt). Intracellular Ca2+ transients were evaluated as fura-2 fluorescent intensity (FFI), excitation-induced change in FFI (DeltaFFI = peak-basal), and fluorescence decay rate (tau). Expression of Ca2+ regulatory proteins SERCA2a, Na+-Ca2+ exchanger (NCX), and phospholamban (PLB) were assessed by reverse transcriptase polymerase chain reaction and Western blot. SHR rats exhibited elevated blood pressure. SHR myocytes displayed decreased PS +/- dL/dt, peak FFI, and DeltaFFI; shortened TPS; prolonged tau with normal TR90; and basal FFI compared with WKY myocytes. Inhibition of SERCA with thapsigargin (5 microM) or CPA (10 microM) significantly depressed PS +/- dL/dt, baseline FFI, and DeltaFFI, and prolonged TPS, TR90, and tau in WKY myocytes. However, SHR myocytes were relatively insensitive to thapsigargin or CPA with only TPS and TR90 prolonged. Both mRNA and protein expressions of NCX and PLB were significantly enhanced, whereas SERCA2a protein abundance was reduced in SHR rats compared with the WKY group. Our data suggest that inhibition of SERCA function differentially affected cardiac contractile function in ventricular myocytes from normotensive and hypertensive rats possibly through reduced SERCA2a, elevated PLB, and NCX expression under hypertension.
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PMID:Inhibition of sarco(endo)plasmic reticulum Ca2+-ATPase differentially regulates contractile function in cardiac myocytes from normotensive and spontaneously hypertensive rats: role of Ca2+ regulatory proteins. 1567 24

Artemisinin-based combination therapies (ACTs) are highly effective for the treatment of Plasmodium falciparum malaria, yet their sustained efficacy is threatened by the potential spread of parasite resistance. Recent studies have provided evidence that artemisinins can inhibit the function of PfATP6, the P. falciparum ortholog of the ER calcium pump SERCA, when expressed in Xenopus laevis oocytes. Inhibition was significantly reduced in an L263E variant, which introduced the mammalian residue into a putative drug-binding pocket. To test the hypothesis that this single mutation could decrease P. falciparum susceptibility to artemisinins, we implemented an allelic-exchange strategy to replace the wild-type pfatp6 allele by a variant allele encoding L263E. Transfected P. falciparum clones were screened by PCR analysis for disruption of the endogenous locus and introduction of the mutant L263E allele under the transcriptional control of a calmodulin promoter. Expression of the mutant allele was demonstrated by reverse transcriptase (RT) PCR and verified by sequence analysis. Parasite clones expressing wild-type or L263E variant PfATP6 showed no significant difference in 50% inhibitory concentrations (IC(50)s) for artemisinin or its derivatives dihydroartemisinin and artesunate. Nonetheless, hierarchical clustering analysis revealed a trend toward reduced susceptibility that neared significance (artemisinin, P approximately = 0.1; dihydroartemisinin, P = 0.053 and P = 0.085; and artesunate, P = 0.082 and P = 0.162 for the D10 and 7G8 lines, respectively). Notable differences in the distribution of normalized IC(50)s provided evidence of decreased responsiveness to artemisinin and dihydroartemisinin (P = 0.02 for the D10 and 7G8 lines), but not to artesunate in parasites expressing mutant PfATP6.
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PMID:Investigations into the role of the Plasmodium falciparum SERCA (PfATP6) L263E mutation in artemisinin action and resistance. 2056 62