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)

The interaction between the Ca2+ transport ATPase and the proteolipid of rabbit sarcoplasmic reticulum was analyzed by fluorescence energy transfer, using the following donor: acceptor combinations: Ca2(+)-ATPase tryptophan----IAEDANS-proteolipid; IAEDANS-ATPase----IAF-proteolipid; IAEDANS-proteolipid----IAF-ATPase. The observed energy transfer may indicate weak interaction between the Ca2(+)-ATPase and proteolipid, but collisional energy transfer definitely contributes. The energy transfer was abolished by deoxycholate or sodium dodecylsulfate at concentrations sufficient to solubilize the membrane. In view of the low proteolipid content of sarcoplasmic reticulum and the weak interaction suggested by the energy transfer, at best only a small fraction of ATPase molecules could exist in the form of ATPase-proteolipid complexes.
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PMID:Interaction between the Ca2(+)-ATPase and the proteolipid in artificial membranes. 253 29

The transmembrane segments predicted for the Neurospora H-ATPase are laid out diagrammatically in Figure 10. Although the eight segments have arbitrarily been compressed into rectangles of the same size, they range in length from 20 residues (II) to 30 residues (IV and VI), so the corresponding helices must vary in length as well. Notable features of the model include the charged residues located just outside the plane of the membrane, with a clear excess of negative charges (5-, 1+) at the extracellular surface and a slight excess of positive charges (4+, 3-) at the cytoplasmic surface. There are also a conspicuous number of bulky residues (tryptophan, phenylalanine, and tyrosine) just inside the plane of the membrane. Within the bilayer, most of the helices are noticeably amphipathic, consistent with the expectation that at least some of them stack together to form a channel-like structure with a hydrophobic surface and a hydrophilic core. The charged residues predicted to lie within the membrane are listed in Table 2, which is a summary of data from eight of the P-type ATPases; the S. cerevisiae and S. pombe enzymes have not been included because they are nearly identical in this respect to the Neurospora enzyme. Interestingly, all of the ATPases have more membrane-embedded negative charges (5 to 8) than positive ones (0 to 4), a pattern that may be connected with their role as cation transporters. Certainly, other unrelated transport proteins have a rather different pattern of positive and negative charges: for example, the mammalian glucose transporter (1+, 2-), Na-glucose transporter (3+, 3-), and the E. coli lac permease (11+, 7-). The actual positioning of the negative charges in the P-type ATPases does not make it easy to single out the functionally important ones, however. The glutamyl residue in segment I is present in the fungal, plant, and Leishmania H-ATPases but not in the gastric H,K-ATPase. The same is true for the aspartate in segment II, except that it also appears in the muscle and brain Ca-ATPases. A glutamate is found at one end of segment III in the E. coli and fungal enzymes and at the other end in Arabidopsis; in segment IV, another glutamate appears in a well-conserved region in the Leishmania and mammalian enzymes but not in the bacterial, fungal, or plant ones.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Transmembrane segments of the P-type cation-transporting ATPases. A comparative study. 256 19

Hexachlorocyclohexanes have been shown to inhibit the (Ca2+ + Mg2+)-ATPase of muscle sarcoplasmic reticulum reconstituted into bilayers of dioleoylphosphatidylcholine. However, for the ATPase reconstituted into bilayers of dimyristoleoylphosphatidylcholine, a pattern of activation at low concentration followed by inhibition at higher concentration is seen for hexachlorocyclohexanes and alkanes such as decane and hexadecane. The ATPase in sarcoplasmic reticulum vesicles is also inhibited by the hexachlorocyclohexanes. The effects of hexachlorocyclohexanes on activity are largely independent of concentrations of Ca2+ and ATP. Inhibition is more marked at lower temperatures. The hexachlorocyclohexanes quench the tryptophan fluorescence of the ATPase, and the quenching can be used to obtain partition coefficients into the membrane system. As for simple lipid bilayers, partition exhibits a negative temperature coefficient. Binding is related to effects on ATPase activity.
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PMID:Interactions of hexachlorocyclohexanes with the (Ca2+ + Mg2+)-ATPase from sarcoplasmic reticulum. 257 11

The effect of magnesium on the phospholipid order parameter and not the conformation of purified pig kidney outer medulla (Na+ + K+)-ATPase was investigated by fluorescence techniques. Measurements with a fluorescent probe TMA-DPH and its sensitized fluorescence with tryptophan residues as donors revealed that magnesium increased the order of the membrane phospholipids both in the lipid annulus and in the bulk phase. Changes in the lipid order induced by Mg2+ can be closely referred to the protein arrangement followed by the steady-state anisotropy of FITC-labeled (Na+ + K+)-ATPase.
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PMID:Mg2+-induced changes of lipid order and conformation of (Na+ + K+)-ATPase. 282 84

The proton pump (H+-ATPase) found in the plasma membrane of the fungus Neurospora crassa is inactivated by dicyclohexylcarbodiimide (DCCD). Kinetic and labeling experiments have suggested that inactivation at 0 degrees C results from the covalent attachment of DCCD to a single site in the Mr = 100,000 catalytic subunit (Sussman, M. R., and Slayman, C. W. (1983) J. Biol. Chem. 258, 1839-1843). In the present study, when [14C]DCCD-labeled enzyme was treated with the cleavage reagent, N-bromosuccinimide, a single major radioactive peptide fragment migrating at about Mr = 5,300 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis was produced. The fragment was coupled to glass beads and partially sequenced by automated solid-phase Edman degradation at the amino terminus and at an internal tryptic cleavage site. By comparison to the DNA-derived amino acid sequence for the entire Mr = 100,000 polypeptide (Hager, K., and Slayman, C. W. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 7693-7697), the fragment has been identified as arising by cleavage at tyrosine 100 and tryptophan 141. Covalently incorporated [14C]DCCD was released at a position corresponding to glutamate 129. The DCCD-reactive glutamate is located in the middle of the first of eight predicted transmembrane sequences. When the sequence surrounding the DCCD site is compared to that surrounding the DCCD-reactive residue of two other proton pumps, the F0F1-ATPase and cytochrome c oxidase, no homology is apparent apart from an abundance of hydrophobic amino acids.
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PMID:Location of a dicyclohexylcarbodiimide-reactive glutamate residue in the Neurospora crassa plasma membrane H+-ATPase. 288 24

2-Hydroxy-5-nitrobenzyl bromide, a highly reactive reagent towards tryptophan residues in proteins, is shown to activate the passive proton flux through the inner mitochondrial membrane of bovine heart submitochondrial particles (ETPH). When added at low concentrations, the reagent increased both the ATPase activity of the particles and the passive proton transport rate through the membrane. The presence of oligomycin reduced the extent of the 2-Hydroxy-5-nitrobenzyl bromide action on the proton conductivity suggesting that it acted primarily on the H+-ATPase complex. Similar effects were observed on F1-depleted particles, whilst no effect was observed on the isolated F1-ATPase activity. The results suggest that polypeptides bearing tryptophan residues may be involved in the gating function of proton channels of the mitochondrial membrane and this is particularly evident for the F0F1-ATPase complex.
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PMID:Effect of 2-hydroxy-5-nitrobenzyl bromide on proton translocation by the mitochondrial H+-ATPase. 290 Dec 60

Cleavage of reduced, carboxymethylated, delipidated CA2+-transporting ATPase protein from rabbit sarcoplasmic reticulum with dimethyl sulphoxide/HBr yielded two long peptides (38 and 73 residues), distinct from the known major sequences of the ATPase. The longer peptide contained at least two cysteine residues, which were disulphide-linked in the native protein. It was therefore derived from the B-fragment of the ATPase in which the disulphides had previously been located. It probably formed a loop on the luminal side of the membrane, spanning two membrane-buried tryptophan residues. The N-terminal sequence of this peptide, (Trp)-Phe-Met-Tyr-Ala, forms the basis for an oligodeoxynucleotide probe, the use of which to identify cDNA corresponding to the ATPase is described elsewhere [MacLennan, Brandl, Korczak & Green (1985) Nature (London) 316, 696-700].
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PMID:The sequence of two peptides isolated from the Ca2+-transporting ATPase of rabbit sarcoplasmic reticulum after cleavage at tryptophan. 293 31

The ATPase of the thermophilic bacterium PS3, TF0F1, and its subunits has been isolated and their absorption and fluorescence spectra have been measured. The following results were obtained: The tryptophan content of the subunits was determined spectroscopically. Although tryptophan (Trp) and tyrosine (Tyr) are found in TF1, the fluorescence spectrum of native TF1 and its subunits is dominated by Tyr fluorescence; this is in contrast to other proteins. Among (native) TF1 and its subunits only TF1 and the alpha-subunit show a weak fluorescence of Trp, which is blue-shifted, indicating a location in a strongly hydrophobic environment. TF0 fluorescence is dominated by the strong Trp fluorescence. TF0F1 fluorescence is also dominated by the Trp residues. Additionally, its fluorescence is higher than the sum of the isolated TF0 and TF1, indicating marked changes in the microenvironment of the fluorescing aminoacids upon binding of TF1 to TF0.
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PMID:Spectroscopic characterization of the ATPase of the thermophilic bacterium PS3 and its isolated subunits. 294 Feb 34

The effect of hydrostatic pressure on the self-association of sarcoplasmic reticulum ATPase solubilized by nonionic detergent was studied in the pressure range of 1 atm up to 2 kilobars. Polarization of intrinsic tryptophan fluorescence or of fluorescence of a pyrene probe covalently attached to the ATPase was measured. An increase in hydrostatic pressure promoted dissociation of the protein into monomers. For a midpoint dissociation pressure of 1.3 kilobars, the standard volume change in the dissociation reaction was delta Vop = -167 ml/mol. Full reversibility of the pressure effects was shown to occur, as seen by recovery of polarization. An increase in Ca2+ concentration from 50 microM to 5 mM and of pH from 6.9 to 8.6 were found to increase the midpoint dissociation pressure, indicating that these factors stabilize the dimeric state. The hydrolytic activity of the ATPase was measured under pressure. The activity was inhibited by pressure increase. It was found that an irreversible inactivation of the solubilized enzyme occurred during turnover and that increasing pressure added to this instability. Reversibility of the activity was critically dependent on the presence of 10 mM Ca2+ in the assay medium.
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PMID:Pressure-induced dissociation of solubilized sarcoplasmic reticulum ATPase. 294 35

We have investigated the kinetics of the intrinsic fluorescence drop observed when ATP is added to purified sarcoplasmic reticulum ATPase in a potassium-free medium containing magnesium and calcium, at pH 6 and 20 degrees C. Under these conditions, analysis of the fluorescence drop is complex. Several events contributed to the rate of the fluorescence drop initiated by turnover, including phosphorylation, conformational transition of the phosphorylated complex, and dephosphorylation. On the other hand, when 75% of total fluorescence was quenched by energy transfer to the membrane-bound ionophore A23187, the observed turnover-dependent drop in residual fluorescence mainly reflected the conformational transition of the phosphorylated ATPase. Combination of fast kinetics with the quenching of selected tryptophan residues is suggested to be a promising tool for the study of proteins containing many of these residues.
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PMID:Does intrinsic fluorescence reflect conformational changes in the Ca2+-ATPase of sarcoplasmic reticulum? 294 63


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