Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is possible to select transmembrane potential (delta psi)-altered mutants in Streptococcus pneumoniae on the basis of their resistance to the antifolate methotrexate. Comparison of such a mutant strain ( amiA9 ) with its parent was used to evaluate the role of delta psi in the uptake of certain amino acids. The delta psi-dependent uptake of isoleucine, leucine, valine, and asparagine showed a reduced maximum velocity of uptake, and decrease in the transport constant of the energy-dependent, delta psi-independent uptake of lysine, methionine, and glutamine was observed. No reduction of the intracellular pool of ATP or of lactate excretion could be detected in the mutant strain. Moreover, studies on membrane preparations suggest that the phenotype expressed by the amiA mutation is not a consequence of alteration of its ATPase activity or susceptibility to N,N'-dicyclohexylcarbodiimide. Therefore, it is unlikely that the amiA mutation affects the H+ F1F0 ATPase which is involved in the establishment of the proton motive force in anaerobic bacteria. We propose that another function contributes to delta psi in S. pneumoniae. The amiA gene may be the structural gene of that function.
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PMID:Characterization of a Streptococcus pneumoniae mutant with altered electric transmembrane potential. 623 66

The structures and functions of the two alpha-actinin isoforms [R. Kobayashi et al. (1983) Eur. J. Biochem. 133, 607-611] isolated from rabbit longissimus dorsi and psoas muscles were compared. One-dimensional and two-dimensional electrophoretic analyses showed that the two alpha-actinins were different from each other in their subunit chain weights and isoelectric points. The Stokes' radius of the longissimus dorsi and psoas alpha-actinins was 7.4 nm and 7.0 nm, respectively. The amino acid analyses showed that, although the two alpha-actinins are similar in their amino acid compositions, longissimus dorsi alpha-actinin contains more aspartic acid and isoleucine than psoas alpha-actinin but fewer glycine and valine residues. Analysis of the soluble tryptic peptides by two-dimensional mapping revealed that the two alpha-actinins had major differences. These data suggested that the two isoforms are the products of at least two different genes. Despite these differences, both alpha-actinins share a number of common properties. Both alpha-actinins contain a 55-kDa peptide resistant to trypsin. The two proteins show no differences in actomyosin turbidity assays. ATPase assays and F-actin binding assays of alpha-actinin activity. Immunological examination indicates that the two alpha-actinins share antigenic determinants in common.
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PMID:Different muscle-specific forms of rabbit skeletal muscle alpha-actinin. 623 79

Subunit 9 (dicyclohexylcarbodiimide binding protein, 'proteolipid') of the mitochondrial F1F0-ATPase is a nuclearly coded protein in Neurospora crassa. It is synthesized on free cytoplasmic ribosomes as a larger precursor with an NH2-terminal peptide extension. The peptide extension is cleaved off after transport of the protein into the mitochondria. A processing activity referred to as processing peptidase that cleaves the precursor to subunit 9 and other mitochondrial proteins is described and characterized using a cell-free system. Precursor synthesized in vitro was incubated with extracts of mitochondria. Processing peptidase required Mn2+ for its activity. Localization studies suggested that it is a soluble component of the mitochondrial matrix. The precursor was cleaved in two sequential steps via an intermediate-sized polypeptide. The intermediate form in the processing of subunit 9 was also seen in vivo and upon import of the precursor into isolated mitochondria in vitro. The two cleavage sites in the precursor molecule were determined. The data indicate that: the correct NH2-terminus of the mature protein was generated, the NH2-terminal amino acid of the intermediate-sized polypeptide is isoleucine in position -31. The cleavage sites show similarity of primary structure. It is concluded that processing peptidase removes the peptide extension from the precursor to subunit 9 (and probably other precursors) after translocation of these polypeptides (or the NH2-terminal part of these polypeptides) into the matrix space of mitochondria.
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PMID:Processing peptidase of Neurospora mitochondria. Two-step cleavage of imported ATPase subunit 9. 623 9

The amino acid sequence of the proteolipid subunit of the ATP synthase was analyzed in six mutant strains from Escherichia coli K12, selected for their increased resistance towards the inhibitor N,N'-dicyclohexylcarbodiimide. All six inhibitor-resistant mutants were found to be altered at the same position of the proteolipid, namely at the isoleucine at residue 28. Two substitutions could be identified. In type I this residue was substituted by a valine resulting in a moderate decrease in sensitivity to dicyclohexylcarbodiimide. Type II contained a threonine residue at this position. Here a strong resistance was observed. These two amino acid substitutions did not influence functional properties of the ATPase complex. ATPase as well as ATP-dependent proton-translocating activities of mutant membranes were indistinguishable from the wild type. At elevated concentrations, dicyclohexylcarbodiimide still bound specifically to the aspartic acid at residue 61 of the mutant proteolipid as in the wild type, and thereby inhibited the activity of the ATPase complex. It is suggested that the residue 28 substituted in the resistant mutants interacts with dicyclohexylcarbodiimide during the reactions leading to the covalent attachment of the inhibitor to the aspartic acid at residue 61. This could indicate that these two residues are in close vicinity and would thus provide a first hint on the functional conformation of the proteolipid. Its polypeptide chain would have to fold back to bring together these two residues separated by a segment of 32 residues.
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PMID:Identification of amino-acid substitutions in the proteolipid subunit of the ATP synthase from dicyclohexylcarbodiimide-resistant mutants of Escherichia coli. 625 67

The photoautotrophic cyanobacterium Anacystis nidulans was used to investigate the membrane transport of branched-chain, neutral amino acids and its dependence on photosynthetic reactions. The uptake of alpha-amino [1-14C]isobutyric acid and L-[1-14C]leucine followed Michaelis, Menten kinetics and resulted in an energy-dependent accumulation. As in bacteria, different uptake systems for neutral amino acids were present: two DAG (D-alanine, aminoisobutyric acid, and glycine) systems responsible for uptake of alpha-amino [1-14C]isobutyric acid, and one LIV (leucine, isoleucine, and valine) system, responsible for uptake of leucine. The low-affinity DAG system seemed to be dependent on the presence of Na+ ions. Uptake was enhanced by white light and by monochromatic light of 630 nm. In far red light (717 nm) with and without nitrogen flushing, considerable uptake dependent on light intensity and inhibition by dibromothymoquinone and by high concentrations of KCN were observed. Therefore, the energy generated by photosystem I reactions only could perform this membrane transport. The proton translocator carbonylcyanide m-chlorophenylhydrazone and N,N-dicyclohexylcarbodiimide as an ATPase inhibitor reduced amino acid uptake to a high degree. A pH dependence of aminoisobutyric acid and leucine uptake was obvious, with a maximum at pH 6 to 7 and some at a pH as high as 9.5. At higher pH, increasing concentrations of Na+ K+ and also of triphenylmethylphosphonium ions inhibited the transport of aminoisobutyric acid. These findings are consistent with the assumption that ATP from photosynthetic reactions drives a membrane-bound proton-translocating ATPase producing a proton motive force, consisting at higher pH chiefly in a delta psi amount, which promotes a secondary active H+ or Na+/amino acid symport carrier.
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PMID:Amino acid uptake and energy coupling dependent on photosynthesis in Anacystis nidulans. 680 40

By use of PCR, the dnaB genes from the classical temperature-sensitive dnaB mutants PC8 (dnaB8), RS162 (dnaB252), CR34/454 (dnaB454), HfrH165/70 (dnaB70), and CR34/43 (dnaB43) were isolated. The mutant genes were sequenced, and single amino acid changes were identified in all cases. The mutant DnaB proteins were overexpressed in BL21 (DE3) cells by using the T7 based pET-11c expression vector system. The purified proteins were compared in regard to activities in the general priming reaction of primer RNA synthesis (with primase and single-stranded DNA [ssDNA] as the template), ATPase activity, and helicase activity at permissive (30 degrees C) and nonpermissive (42 degrees C) temperatures. The DnaB252 mutation is at amino acid 299 (Gly to Asp), and in all in vitro assays the DnaB252 protein was as active as the wild-type DnaB protein at both 30 and 42 degrees C. This region of the DnaB protein is believed to be involved in interaction with the DnaC protein. The dnaB8, dnaB454, and dnaB43 mutations, although independently isolated in different laboratories, were all at the same site, changing amino acid 130 from Ala to Val. This mutation is in the hinge region of the DnaB protein domains and probably induces a temperature-sensitive conformational change. These mutants have negligible primer RNA synthesis, ATPase activity, and helicase activity at the nonpermissive temperature. DnaB70 has a mutation at amino acid 242 (Met to Ile), which is close to the proposed ATP binding site. At 30 degrees C this mutant protein has a low level of ATPase activity (approximately 25% of that of the wild type) which is not affected by high temperature. By using a gel shift method that relies upon ssDNA substrates containing the photoaffinity analog 5-(N-(p-azidobenzoyl)-3-aminoallyl)-dUMP, all mutant proteins were shown to bind to ssDNA at both 30 and 42 degrees C. Their lack of other activities at 42 degrees C, therefore, is not due to loss of binding to the ssDNA substrate.
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PMID:Biochemical characterization of Escherichia coli temperature-sensitive dnaB mutants dnaB8, dnaB252, dnaB70, dnaB43, and dnaB454. 753 69

Because of the conflicting conclusions that have been reached regarding the location of the two putative membrane-spanning segments from cysteine 911 through isoleucine 929 and from isoleucine 946 through cysteine 964 in the alpha subunit of native ovine Na+/K(+)-transporting ATPase, the disposition of lysine 943 with respect to the plane of the lipid bilayer was investigated. Sealed, right-side-out vesicles were modified with pyridoxal phosphate and Na[3H]BH4 in the presence and absence of saponin, a reagent that creates holes in the membranes. Modified alpha polypeptide was isolated, and digested with trypsin and chymotrypsin to release the desired peptides, QQGMK and QQGMK([3H]pyr)NK (where [3H]pyr designates the modification on lysine 943). These peptides, after cyclization of their amino-terminal glutamines, were isolated with an immunoadsorbent specific for the amino-terminal sequence pyroglutamyl-QGM-followed by high-pressure liquid chromatography on a C-18 reverse phase column. Comparisons were made of the extent of incorporation of radioactivity into lysine 943 between sealed vesicles and sealed vesicles pretreated with saponin. An increase in incorporation into lysine 943 of 5-fold to 18-fold was seen in vesicles pretreated with saponin prior to the modification with pyridoxal phosphate. This increase in incorporation is consistent with a cytoplasmic location for lysine 943. This conclusion places the residues on the carboxy-terminal side of the putative membrane-spanning segment from cysteine 911 through isoleucine 929 and the amino-terminal side of the putative membrane-spanning segment from isoleucine 946 through cysteine 964 in the ovine alpha subunit on the cytoplasmic side of the membrane.
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PMID:Topological disposition of lysine 943 in native Na+/K(+)-transporting ATPase. 762 20

Human sera from autoimmune gastritis patients containing autoantibodies to gastric parietal cells were analyzed by immunological methods. Enzyme linked immuno-sorbent assay demonstrated that all nine sera reacted with pig gastric vesicles enriched in H+/K(+)-ATPase (gastric proton pump). Immunoblotting experiments indicated that the alpha subunit of the H+/K(+)-ATPase was the major antigen in the vesicles with two of the sera reacting strongly. We further characterized the specificity of the antibodies using partial sequences of the pig alpha subunit fused with truncated TrpE (anthranilate synthase). The antibodies from autoimmune gastritis patients reacted differently to the two fusion proteins (Met-1 to Ala-79, and Arg-606 to Ile-964), indicating that each patient sera contains a mixture of autoantibodies recognizing different epitopes with variable contents.
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PMID:Characterization of human autoantibodies reactive to gastric parietal cells. 767 90

A Kluyveromyces lactis strain resistant to ethidium bromide and deficient in potassium uptake was isolated. Studies on the proton-pumping activity of the mutant strain showed that a decreased H(+)-ATPase specific activity was responsible for the observed phenotypes. The putative K. lactis PMA1 gene encoding the plasma membrane H(+)-ATPase was cloned by its ability to relieve the potassium transport defect of this mutant and by reversing its resistance to ethidium bromide. Its deduced amino acid sequence predicts a protein 899 residues long that is structurally colinear in its full length to H(+)-ATPases cloned from different yeasts, except for the presence of a variable N-terminal domain. By PCR-mediated amplification, we identified a transition from G to A that rendered the substitution of the fully conserved methionine at position 699 by isoleucine. We attribute to this amino acid change the low capacity of the mutant H(+)-ATPase to pump out protons.
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PMID:Molecular cloning of the plasma membrane H(+)-ATPase from Kluyveromyces lactis: a single nucleotide substitution in the gene confers ethidium bromide resistance and deficiency in K+ uptake. 773 Feb 65

The chaperones GroEL/hsp60 are present in all prokaryotes and in mitochondria and chloroplasts of eukaryotic cells. They are involved in protein folding, protein targeting to membranes, protein renaturation, and control of protein-protein interactions. They interact with many polypeptides in an ATP-dependent manner and possess a peptide-dependent ATPase activity. GroEL/hsp60 cooperates with GroES/hsp10, and the productive folding of proteins by GroEL generally requires GroES, which appears to regulate the binding and release of substrate proteins by GroEL. In a recent study, we have shown that GroEL interacts preferentially with the side chains of hydrophobic amino acids (Ile, Phe, Val, Leu, and Trp) and more weakly with several polar or charged amino acids, including the strongest alpha-helix and beta-sheet formers (Glu, Gln, His, Thr, and Tyr). In this study, we show that GroES reduces the specificity of GroEL for hydrophobic amino acids and increases its specificity for hydrophilic ones. This shift by GroES of the GroEL specificity from hydrophobic amino acids toward hydrophilic ones might be of importance for its function in protein folding.
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PMID:Reversal by GroES of the GroEL preference from hydrophobic amino acids toward hydrophilic amino acids. 773 93


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