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

---

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

The stability of dopamine-sensitive adenylate cyclase, guanylate cyclase, ATPase, and GTPase was measured in homogenates of rat striatal tissue frozen from 0 to 24 h postmortem. ATPase, GTPase, and Mg2+-dependent guanylate cyclase activities showed no significant change over this period. Mn2+-dependent guanylate cyclase activity was stable for 10 h postmortem. Basal and dopamine-stimulated adenylate cyclase activity decreased markedly during the first 5 h. However, when measured in washed membrane preparations, these adenylate cyclase activities remained stable for at least 10 h. Therefore, the postmortem loss of a soluble activator, such as GTP, may decrease the adenylate cyclase activity in homogenates. These results are not consistent with an earlier suggestion that there is a postmortem degradation of the enzyme itself. Other kinetic parameters of dopamine-sensitive adenylate cyclase can also be measured independently of postmortem changes. Thus, it is possible to investigate kinetic parameters of dopamine-sensitive adenylate cyclase, guanylate cyclase, ATPase, and GTPase in human brain obtained postmortem.
...
PMID:Postmortem stability of dopamine-sensitive adenylate cyclase, guanylate cyclase, ATPase, and GTPase in rat striatum. 612 Sep 96

Deciliation of Paramecium tetraurelia by a Ca2+ shock procedure releases a discrete set of proteins which represent about 1% of the total cell protein. Marker enzymes for cytoplasm (hexokinase), endoplasmic reticulum (glucose-6-phosphatase), peroxisomes (catalase), and lysosomes (acid phosphatase) were not released by this treatment. Among the proteins selectively released is a Ca2+-dependent ATPase. This enzyme has a broad substrate specificity which includes GTP, ATP, and UTP, and it can be activated by Ca2+, Sr2+, or Ba2+, but not by Mg2+ or by monovalent cations. The crude enzyme has a specific activity of 2-3 mumol/min per mg; the optimal pH for activity is 7.5. ATPase, GTPase, and UTPase all reside in the same protein, which is inhibited by ruthenium red, is irreversibly denatured at 50 degrees C, and which has a sedimentation coefficient of 8-10 S. This enzyme is compared with other surface-derived ATPases of ciliated protozoans, and its possible roles are discussed.
...
PMID:A Ca2+-activated ATPase specifically released by Ca2+ shock from Paramecium tetraurelia. 612 13

Vacuoles of yeast grown in peptone medium possessed high ATPase activity (up to 1 mumol X mg protein-1 X min-1). Membrane-bound and solubilized ATPase activities were insensitive to vanadate and azide, but were inhibited by NO-3 . K+ and cyclic AMP stimulated both membrane-bound and solubilized ATPase activities. Dio-9 activated the membrane form of vacuolar ATPase 1.5-2-fold and did not affect the solubilized enzyme. Solubilized and partially purified vacuolar ATPase was reconstituted with soy-bean phospholipids by a freeze-thaw procedure. ATPase activities in native vacuoles and proteoliposomes were stimulated effectively by Dio-9, the protonophore FCCP and ionophores valinomycin and nigericin. ATP-dependent H+ transport into proteoliposomes was also shown by quenching of ACMA fluorescence. Vacuolar and partially purified ATPase preparations possessed also GTPase activity. Unlike ATPase, however, GTPase was not incorporated as a proton pump into liposomes.
...
PMID:Some properties of membrane-bound, solubilized and reconstituted into liposomes H+-ATPase of vacuoles of Saccharomyces carlsbergensis. 614 72

It was previously observed that the hydrolysis of GTP by cardiac sarcoplasmic reticulum (SR) (in contrast to skeletal muscle SR: (a) was identical in rate with total ATP hydrolysis; (b) gave a similar nonlinear substrate response; (c) was not Ca2+ dependent; and (d) stimulated Ca2+ accumulation but not Ca2+ translocation. Evidence was presented that both the ATPase and GTPase are effected by the same enzyme and represent different hydrolysis cycles (Van Winkle, W. B., Tate, C. A., Bick, R. J., and Entman, M. L. (1981) J. Biol. Chem. 256, 2268-2274). In the present paper, we report that purification of the NTPase from both muscle sources resulted in an alteration in the NTP concentration response compatible with a single high affinity binding site for ATP only in cardiac SR and for both substrates in skeletal muscle SR. As is the case with native skeletal muscle SR, purified skeletal muscle NTPase hydrolyzed GTP in a manner qualitatively similar to ATP (but with no Ca2+-independent NTPase) but with reduced velocity. In contrast, there was no GTPase activity or Ca2+-independent "basic" ATPase activity in the purified cardiac NTPase. Inclusion of oxalate or the ionophore, A23187, in assays with cardiac SR and ATP as the substrate increased the total ATPase activity but had no effect on GTPase activity. Furthermore, the nucleotide-dependent uptake of oxalate by cardiac SR was only apparent with ATP and not with GTP. In the presence of Ca2+, ATP was a potent inhibitor (noncompetitive, Ki of 2-5 microM) of GTPase activity, whereas it was a weaker competitive inhibitor in the absence of Ca2+. We suggest that GTPase and basic ATPase represent similar alternative enzyme cycles for the CaATPase enzyme that are inhibited by the presence of ATP plus Ca2+ but are rendered inactive during the purification of cardiac NTPase.
...
PMID:Nucleotide triphosphate utilization by cardiac and skeletal muscle sarcoplasmic reticulum. Further evidence for an alternative substrate hydrolysis cycle and the effect of calcium NTPase purification. 630 87

Rod outer segments (ROSs) of vertebrate photoreceptor cells have been reported to contain several enzyme systems including a dark, Ca2+-stimulated ATPase, a rhodopsin kinase, a phosphodiesterase and a GTPase, all of which are light-stimulated. Recently, Thacher has found a light-stimulated Mg2+-ATPase in frog ROSs while our own laboratory has identified a dark, Ca2+-inhibited Mg2+-ATPase in bovine ROSs. Here we extend our observations on the Mg2+-ATPase and demonstrate that flash illumination following the dark ATPase process stimulated ATPase activity at a rate considerably faster than the dark process. In addition, we find that both the dark and light stimulated ATPase activities are markedly enhanced by cyclic GMP and inhibited by Ca2+.
...
PMID:Cyclic GMP stimulation of a light-activated ATPase in rod outer segments. 631 Apr 4

Treatment of isolated factor F1 by 1% dimethylsuberimidate in the presence of 50 mM (NH4)2SO4 leads to the formation of four different types of cross-linked dimers of the subunits, on average one dimer per molecule of the enzyme. This treatment results in 60-70% inactivation of factor F1. Factor F1 treated with dimethylsuberimidate does not show a change in the sedimentation coefficient and is not inactivated in the cold; it is not inactivated in the presence of Mg2+ either, nor is it activated by anions. Incubation of the cross-linked factor F1 with ADP does not lead to inactivation, although the ability to tightly bind ADP is retained. The total quantity of tightly bound ADP reaches 5 mol per mol of the cross-linked factor F1. Cross-linking of factor F1 also prevents the slow inactivation of the enzyme coupled with the hydrolysis of Mg-ATP and Mg-GTP. The dependence of the inactivation rate constant on the concentration of Mg-ATP and Mg-GTP at substrate concentrations of 0.05-2 mM is characterized by the same values of Km,app as those of the ATPase and GTPase activities of factor F1. The probability of the inactivation of factor F1 per turnover remains constant for all the concentrations of the substrates studied and is 2 . 10(-6) per turnover for the ATPase reaction and 2 . 10(-5) per turnover for the GTPase reaction. Moderate hydrostatic pressure (up to 150 atmospheres) greatly accelerates ATP-induced inactivation of factor F1. The activation volume (delta V*) of the inactivation process is equal to 5.1 . 10(-4) cm3/g, which is evidence of considerable changes in the extent of protein hydration during inactivation. Inactivation of the enzyme under pressure is accompanied by dissociation into subunits. Dimethyladipimidate, which does not cause intersubunit cross-linking in the molecule of factor F1, does not alter the properties of the native enzyme. It is suggested that the formation of one intersubunit cross-link in the molecule of factor F1 by dimethylsuberimidate affects the ability of the enzyme to undergo co-operative rearrangements of the quaternary structure under the influence of Mg2+, ADP, ATP, anions, and low temperature. The rate constants of ATP binding to the active site of factor F2 (k+1) = 2 . 10(8) M-1 . min-1), of ATP release from the active site (k-1 = 2 . 10(-2) min-1), and of ADP and Pi release from the active site (k2 = 5 . 10(3) min-1) have been determined. The results obtained confirm the correctness of Boyer's idea, according to which ATP is formed in the active site of mitochondrial ATPase without any external source of energy. Energy is used at the stage of the release of synthesized ATP from the active site of ATPase in the solution.
...
PMID:Structural rearrangements in soluble mitochondrial ATPase. 645 13

Elongation factor 3 from the yeast Saccharomyces cerevisiae was purified over 230-fold from a high speed supernatant fraction. The homogeneity of the protein was shown by gel filtration and sedimentation equilibrium analysis of the native protein and by sodium dodecyl sulfate gel electrophoresis of the denatured protein. The molecular weight of the protein was estimated to be 125,000 by the above-mentioned methods. The protein consists of a single polypeptide chain. Amino acid analysis revealed no unusual features. Antibody raised against the purified factor showed a single cross-reacting band with the characteristic hexagonal pattern in an Ouchterlony double diffusion plate. The immune serum had no reactivity against the other two elongation factors (EF). The polymerization reaction was inhibited by the anti-EF3. Addition of excess EF3 could overcome this effect. Factor 3 is absolutely required by the yeast ribosomes for polyphenylalanine synthesis. Ribosomes from other eukaryotes do not require this protein. The function of the third factor in polyphenylalanine synthesis cannot be defined at this time. The protein showed ribosome-dependent GTPase and ATPase activities. Studies of partial reactions showed that EF3 was not required for Phe-tRNA binding to ribosomes, peptide bond formation, or translocation. Nucleotide exchange by EF1 was not stimulated by EF3.
...
PMID:Protein synthesis in yeast. I. Purification and properties of elongation factor 3 from Saccharomyces cerevisiae. 645 69

A new method for separating microtubule-associated proteins (MAPs) and tubulin, appropriate for relatively large-scale preparations, was developed. Most of the active tubulin was separated from the MAPs by centrifugation after selective polymerization of the tubulin was induced with 1.6 M 2-(N-morpholino)ethanesulfonate (Mes) and GTP. The MAPs-enriched supernatant was concentrated and subsequently clarified by prolonged centrifugation. The supernatant (total soluble MAPs) contained almost no tubulin, most of the nucleosidediphosphate kinase activity of the microtubule protein, good activity in promoting microtubule assembly in 0.1 M Mes, and proteins with the electrophoretic mobility of MAP-1, MAP-2, and tau factor. The pellet, inactive in supporting microtubule assembly, contained denatured tubulin, most of the ATPase activity of the microtubule protein, and significant amounts of protein with the electrophoretic mobility of MAP-2. Insoluble material at this and all previous stages, including the preparation of the microtubule protein, could be heat extracted to yield soluble protein active in promoting microtubule assembly and containing MAP-2 as a major constituent. The total soluble MAPs were further purified by DEAE-cellulose chromatography into bound and unbound components, both of which induced microtubule assembly. The bound component (DEAE-MAPs) contained proteins with the electrophoretic mobility of MAP-1, MAP-2, and tau factor. The polymerization reaction induced by the unbound component (flow-through MAPs) produced very high turbidity readings. This was caused by the formation of bundles of microtubules. Although the flow-through MAPs contained significantly more ATPase, tubulin-independent GTPase, and, especially, nucleosidediphosphate kinase activity than the DEAE-MAPs, preparation of a MAPs fraction without these enzymes required heat treatment.
...
PMID:Separation of active tubulin and microtubule-associated proteins by ultracentrifugation and isolation of a component causing the formation of microtubule bundles. 648 96

Fungi appear to be unique in their requirement for a third soluble translation elongation factor. This factor, designated elongation factor 3 (EF-3), exhibits ribosome-dependent ATPase and GTPase activities that are not intrinsic to the fungal ribosome but are nevertheless essential for translation elongation in vivo. The EF-3 polypeptide has been identified in a wide range of fungal species and the gene encoding EF-3 (YEF3) has been isolated from four fungal species (Saccharomyces cerevisiae, Candida albicans, Candida guillermondii, and Pneumocystis carinii). Computer-assisted analysis of the predicted S. cerevisiae EF-3 amino acid sequence was used to identify several potential functional domains; two ATP binding/catalytic domains conserved with equivalent domains in members of the ATP-Binding Cassette (ABC) family of proteins, an amino-terminal region showing significant similarity to the E. coli S5 ribosomal protein, and regions of predicted interaction with rRNA, tRNA, and mRNA. Furthermore, EF-3 was also found to display amino acid similarity to myosin proteins whose cellular function is to provide the motive force of muscle. The identification of these regions provides clues to both the evolution and function of EF-3. The predicted functional regions are conserved among all known fungal EF-3 proteins and a recently described homologue encoded by the Chlorella virus CVK2. We propose that EF-3 may play a role in the ribosomal optimization of the accuracy of fungal protein synthesis by altering the conformation and activity of a ribosomal "accuracy center," which is equivalent to the S4-S5-S12 ribosomal protein accuracy center domain of the E. coli ribosome. Furthermore, we suggest that EF-3 represents an evolving ribosomal protein with properties analogous to the intrinsic ATPase activities of higher eukaryotic ribosomes, which has wider implications for the evolutionary divergence of fungi from other eukaryotes.
...
PMID:Translation elongation factor-3 (EF-3): an evolving eukaryotic ribosomal protein? 756 24

Magnetic isolation of endocytic vesicles from Dictyostelium discoideum was accomplished after feeding the amoebae with iron oxide particles. Proteins associated with the endocytic vesicles were resolved by SDS-PAGE and digested 'in-gel' with endoproteinase Lys-C or Asp-N to generate peptides for amino acid sequencing. This strategy allowed the identification of the major protein constituents of the vesicles: namely, the A, B, D, E and 110 kDa subunits of a vacuolar type H(+)-ATPase, actin, a Rab 7-like GTPase, a p34 protein corresponding to a new cysteine proteinase and the 25 kDa product of a recently sequenced D. discoideum open reading frame.
...
PMID:Identification of major proteins associated with Dictyostelium discoideum endocytic vesicles. 759 93


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

---