Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pH optimum of the ATPase activity in plasma membranes from Saccharomyces cerevisiae NCYC 431 from 8 h cultures was around 6.5 and that in membranes from organisms from 16 h cultures near 6.0. The Km[ATP] of the enzyme was virtually unaffected by the age of the culture from which organisms were harvested, although the Vmax of the enzyme in membranes from organisms from 8 h cultures was higher than that for organisms from 16 h cultures. Ethanol non-competitively inhibited ATPase activity in membranes, although the inhibition constant for the enzyme from organisms from 8 h cultures was lower than that from organisms from 16 h cultures. Glycine accumulation by the general amino acid permease was non-competitively inhibited by ethanol. Inhibition constants were virtually the same for glycine uptake by deenergized organisms from 8 h and 16 h cultures, but under energized conditions the value was greater for organisms from 16 h rather than 8 h cultures. The data indicate that inhibition of plasma-membrane ATPase activity by ethanol could account, at least in part, for inhibition of glycine accumulation by ethanol.
 ...
PMID:Effect of ethanol on activity of the plasma-membrane ATPase in, and accumulation of glycine by, Saccharomyces cerevisiae. 295 98

Skeletal muscle troponin C (TNC) is structured into two separate domains linked by a nine-turn alpha-helix (D/E helix). It has been demonstrated that calcium binding to the regulatory sites within the N-terminal domain induces conformational changes in the C-terminal domain of isolated TNC. Since the only contact between the two domains is the long D/E helix, the transfer of information must involve conformational changes within this helix. The center of the helix is occupied by a glycine (Gly-92). A postulated mechanism for allowing interdomain interaction involves a conformational change of the D/E helix around Gly-92 (Herzberg, O., and James, M. N. G. (1985) Nature 312, 653-659). We tested this hypothesis using site-directed mutants of troponin C. Two separate mutants containing an alanine and a proline replacing Gly-92 were constructed and compared with wild type TNC. Calcium binding studies showed no significant differences among the TNC species. The different TNC were assembled into thin filaments and used to assay the calcium regulation of actin-activated ATPase of myosin. All TNC species were able to mediate the calcium regulation of ATPase. Under the conditions used for the assays, no differences were detected among the TNC species. These results show that Gly-92 is not essential for the proper interaction of the calcium regulatory sites with the other components of the thin filament, and therefore exclude a large rotation around Gly-92 as the mechanism of information transfer between the two domains of troponin C.
 ...
PMID:Cloning, expression, and site-directed mutagenesis of chicken skeletal muscle troponin C. 296 2

The gastric H,K-ATPase is an active transport protein that is responsible for the maintenance of a large pH gradient across the secretory canaliculus of the mammalian parietal cell. Acid secretion across these epithelial cell membranes is coupled to the potassium-stimulated hydrolysis of ATP catalyzed by H,K-ATPase, but the mechanism of coupling between ion transport and ATP hydrolysis is unknown. In order to investigate the enzymatic mechanism of this coupling, a peptide derived from the ATP binding site of H,K-ATPase has been purified and its amino acid sequence has been determined. The peptide was identified by the incorporation of a fluorescent probe, fluorescein 5'-isothiocyanate (FITC), into the active site before trypsin digestion of the protein. The labeling of the enzyme by FITC was associated with the irreversible inhibition of enzymatic activity, and both the labeling of the tryptic peptide and inhibition of activity were prevented when the reaction was performed in the presence of ATP. At 100% inhibition of activity, 3.5 +/- 1.6 nmol of FITC were incorporated per mg of protein. The amino acid sequence of the active site peptide is His-Val-Leu-Val-Met-Lys-Gly-Ala-Pro-Glu-Gln-Leu-Ser-Ile-Arg, and FITC reacts with the lysine. This sequence is very similar to sequences of fluorescein-labeled peptides from the ATP binding sites of Na,K-ATPase and Ca2+-ATPase, and suggests that the active site structures of these ion transport ATPases are similar.
 ...
PMID:The amino acid sequence of an active site peptide from the H,K-ATPase of gastric mucosa. 298 87

A hepta-peptide, Arg-Leu-Leu-Pro-Ser-Leu-Gly, which has a sequence involved in the extra peptides of mitochondrial proteins, was synthesized chemically. The peptide was found to bind specifically to mitochondria, but not to microsomes. The binding was blocked by pretreatment of mitochondria with trypsin but was not affected by the presence of apocytochrome c. The synthetic peptide inhibited the binding to mitochondria of the precursor protein of ATPase inhibitor, which was synthesized in vitro, but did not inhibit that of the precursor of the 9 K stabilizing factor, which has an entirely different extra-peptide sequence. The peptide also did not inhibit the binding of apocytochrome c. These results suggest the existence of a common protein receptor on mitochondrial membranes that facilitates entrance of a group of mitochondrial precursor proteins, including pre-ATPase inhibitor.
 ...
PMID:Interaction with mitochondrial membranes of a synthetic peptide with a sequence common to extra peptides of mitochondrial precursor proteins. 298 25

(Na,K)-ATPase from Torpedo californica (electric ray) and Artemia salina (brine shrimp) was labeled with fluorescein 5'-isothiocyanate (FITC) with concomitant loss of activity. Both inactivation and binding were inhibited in the presence of ATP. The sequence of the peptide resulting from tryptic digest containing labeled lysine from both enzymes is Tyr-Leu-Leu-Val-Met-Lys*-Gly-Ala-Pro-Glu-Arg. Thus the primary structure of this region is shown to be conserved in the enzymes of a nonvertebrate and a vertebrate.
 ...
PMID:The amino acid sequence of the fluorescein-labeled peptides of electric ray and brine shrimp (Na,K)-ATPase. 299 63

The sequences of the first 14 amino acids of the (Na+,K+)-ATPase catalytic subunits from rat kidney (alpha) and rat brain axolemma (alpha(+)) have been determined. They are: (alpha), NH2-Gly-Arg-Asp-Lys-Tyr-Glu-Pro-Ala-Ala-Val-Ser-Glu-His-Gly; (alpha(+)), NH2-Gly-Arg-Glu-Tyr-Ser-Pro-Ala-Ala-Glu-Val-Ala-Glu-Val-Gly. Although they are highly homologous, it is clear these sequences are also sufficiently different to conclude they are the products of different genes, or at least different exons of the same, differentially spliced, gene. Among mammals, the amino terminal sequence of the kidney alpha chain is essentially invariant. Thus this section of the (Na+,K+)-ATPase molecule is more highly conserved in one tissue between several species than between different tissues in the same species. This may reflect upon the difference in function of the alpha and alpha(+) isozymes of (Na+,K+)-ATPase.
 ...
PMID:The catalytic subunits of the (Na+,K+)-ATPase alpha and alpha(+) isozymes are the products of different genes. 299 84

The components of the proton motive force (delta p), namely the membrane potential and the transmembrane pH gradient, were measured in washed cells of Rhizobium japonicum CC705 grown in cultures (5% O2-95% N2) in the presence of 10 mM KNO3 and in bacteroids from Glycine max. The delta p and its components remained reasonably constant in cells as well as in bacteroids at various stages of growth. The effects of uncouplers and ATPase inhibitors on the delta p and its components were determined in both cultured cells and bacteroids. The data indicated that a respiration-driven H+ translocation is the source of the delta p in both cultured cells and bacteroids.
 ...
PMID:Proton motive force in washed cells of Rhizobium japonicum and bacteroids from Glycine max. 299 86

Three methods were used to assess protein concentration in membrane-bound Na,K-ATPase preparations: standard Lowry assay, Kjeldahl nitrogen determination and amino acid analysis. While the first two methods showed excellent agreement, the third one always gave a lower value which varied drastically depending on the condition of sample treatment before amino acid analysis. This result reinforces the Lowry method in assessing the true concentration of Na,K-ATPase protein and suggests 250 kDa to be a true estimate of the molecular mass of the smallest ligand-binding unit of the enzyme. The cyanate method reveals two NH2-terminal residues of the beta-subunit (NH2-Ala) and one such residue of the alpha-subunit (NH2-Gly) per ligand-binding unit. From the data on equimolarity of the alpha- and beta-subunits in Na,K-ATPase this suggests that the enzyme molecule is composed of two alpha beta-protomers, one possessing a modified (presumably an N-blocked) alpha-subunit.
 ...
PMID:Evidence for a diprotomeric structure of Na,K-ATPase. Accurate determination of protein concentration and quantitative end-group analysis. 300 59

Irreversible inhibition of Na,K-ATPase and K+-dependent p-nitrophenylphosphatase activities was produced by incubation of purified Na,K-ATPase enzyme with 1-ethyl-3(3-dimethylaminopropyl)carbodiimide (EPC). Inhibition was time and [EPC] dependent and displayed first order kinetics with respect to time. The [EPC] to reduce the enzyme velocity by 50% for Na,K-ATPase and phosphatase activities was 1.6 and 2.2 mM, respectively. Analysis of the kinetics of inhibition by EPC indicated that reaction at one site was sufficient to produce inhibition. Inhibition was greatly reduced by the presence of Mg2+, Na+, K+, choline, or Tris (decreasing order of effectiveness); ATP was without effect. This suggests that cation-bound enzyme forms were less reactive with the carbodiimide than free enzyme; ATP-bound enzyme was as reactive. Apparently the cations Na+, Mg2+, Tris, and choline stabilize E1 forms of the enzyme which are different from the E1 form stabilized by ATP. Addition of [14C]glycine ethyl ester (Gly-OEt) resulted in incorporation of radioactivity into both alpha and beta subunits that was dependent upon the presence of EPC, and the incorporation was reduced by the cations which reduced the inhibition due to EPC. Simultaneous addition of Gly-OEt with EPC prevented inhibition, although 14C incorporation still took place. If Gly-OEt addition was delayed the initial inactivation was not affected, but little subsequent inactivation occurred. The protection against inactivation by EPC occurs on the addition of other exogenous nucleophiles, such as aminoethane or ethylenediamine. Dicyclohexylcarbodiimide, a more potent hydrophobic carbodiimide inhibitor, shows similar effects; the inhibition due to dicyclohexylcarbodiimide is also prevented by the simultaneous presence of a nucleophile. After treatment with a carbodiimide and exogenous nucleophile the Na,K-ATPase has modified carboxyl residues but is not inhibited. Thus, modification of the cation-protectable carboxyl groups does not by itself cause inhibition. It seems likely that the inhibition of activity due to carbodiimide alone is not due to the modification of a carboxyl group per se but to the formation of an intramolecular bond between the carbodiimide-activated carboxylic acid and an endogenous nucleophile. The formation of such bonds suggests the close juxtaposition of amine and carboxyl groups in the secondary structure of the enzyme.
 ...
PMID:Carbodiimide inactivation of Na,K-ATPase. A consequence of internal cross-linking and not carboxyl group modification. 300 96

Na+,K+-ATPase from pig kidney was specifically modified with a sulfhydryl fluorescent reagent, N-[p-(2-benzimidazolyl)phenyl]maleimide (BIPM), by pretreatment of N-ethylmaleimide. The preparation thus obtained retained 100% of initial Na+,K+-ATPase activity and contained 1 BIPM residue/alpha-chain, and it showed almost 2-fold larger fluorescence changes accompanying ATP hydrolysis than the previous preparations which retained 60% of initial activity and contained 3-4 BIPM residues/alpha-chain (Taniguchi, K., Suzuki, K., and Iida, S. (1982) J. Biol. Chem. 257, 10659-10667). Extensive trypsin (Sigma type I) treatment of the new preparation produced mainly two different fluorescent peptide peaks in both ion-exchange and reverse-phase chromatography. Amino acid sequence analysis of both peptides showed that they had the same common sequence, Ser-Tyr-X-Pro-Gly-Met-Gly-Val, except that the larger one contained Ala-Leu next to the Val residue. From the comparison of the amino acid sequence deduced from cDNA from sheep kidney (Shull, G. E., Schwartz, A., and Lingrel, J. B. (1985) Nature 316, 691-695), X was shown to correspond to Cys-964 of the alpha-chain in Na+,K+-ATPase. The data suggest that the microenvironment of the BIPM residue covalently bound to the sulfhydryl group of Cys-964 changes accompanying sequential appearance of reaction intermediates of Na+,K+-ATPase.
 ...
PMID:Identification of N-[p-(2-benzimidazolyl)phenyl]maleimide-modified residue participating in dynamic fluorescence changes accompanying Na+,K+-dependent ATP hydrolysis. 302 27


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>