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)

We have isolated cDNA clones encoding the bovine and rat gastric H,K-ATPase beta subunit. A bovine abomasum lambda gt11 cDNA library was screened with a monoclonal antibody raised against the rabbit H,K-ATPase beta subunit. A single positive phage clone containing an approximately 900-base pair cDNA insert was identified as reactive with the antibody. The identity of the cDNA was established by comparing the deduced amino acid sequence with sequences of cyanogen bromide fragments of the porcine H,K-ATPase beta subunit. Polymerase chain reaction and rapid amplification of cDNA ends were used to generate a cDNA fragment encoding the carboxyl-terminal portion of the rat gastric H,K-ATPase beta subunit. A rat stomach cDNA library was screened with the polymerase chain reaction product, and several full-length beta subunit cDNA clones were identified. The open reading frame predicts a protein of 294 amino acids with a molecular weight of 33,689. The rat H,K-ATPase beta subunit shows 41% amino acid sequence identity to the rat Na,K-ATPase beta 2 subunit and shares a number of structural similarities with Na,K-ATPase beta subunit isoforms. By analyzing the segregation of restriction fragment length polymorphisms among recombinant inbred strains of mice, we localized the H,K-ATPase beta subunit gene to murine chromosome 8. Northern and Western blot analysis reveals that this gene is expressed exclusively in stomach. Our results suggest that the H,K-ATPase and Na,K-ATPase beta subunits evolved from a common ancestral gene and may play similar functional roles in enzyme activity.
...
PMID:Cloning of the H,K-ATPase beta subunit. Tissue-specific expression, chromosomal assignment, and relationship to Na,K-ATPase beta subunits. 197 34

Prostacyclin (PGI2) did not alter the basal perfusion pressure in the isolated rat mesenteric arteries perfused with Krebs' solution, but produced a biphasic effect in arteries preconstricted with norepinephrine or arginine vasopressin: constriction, then prolonged dilation. Both these components of PGI2 effect were diminished in arteries denuded of their endothelia by a 10 min perfusion with distilled water or p-bromophenacyl bromide (10 microM). The present study elucidates the mechanism of these PGI2 actions. Indomethacin (0.28 microM) SQ 29548 (1 microM, thromboxane A2 receptor antagonist), saralasin (1 microM, angiotensin II receptor antagonist) or the free radical scavengers, superoxide dismutase (60 U/ml) and catalase (40 U/ml) did not inhibit the initial vasoconstriction, suggesting it was not mediated through endothelially generated thromboxane A2, angiotensin II or oxygen-derived free radicals. However, ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid (50 microM; Ca++ chelating agent), 8-(diethyl-amino)octyl 3,4,5-trimethoxy benzoate (10 microM; intracellular Ca++ antagonist), or neomycin (5 mM; phospholipase-C inhibitor) abolished the vasoconstriction. Ouabain (0.5 mM) did not affect the vasodilation, but perfusion with excess (50 mM) or 0 K+ Krebs' solution abolished it, suggesting this PGI2 action involves changes in membrane K+ conductance via a mechanism independent of Na+/K+ adenosine triphosphatase. Vasodilation evoked by BRL 34915 (K+ channel activator) was similarly attenuated under these conditions, but not by ouabain. Furthermore, procaine (1 mM; nonspecific K+ channel inhibitor), but not apamin (0.5 microM) or tetraethylammonium (10 mM) blocked PGI2- and BRL 34915-induced vasodilation.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Mechanism of vascular actions of prostacyclin in the rat isolated perfused mesenteric arteries. 210 93

The bovine heart mitochondrial F1-ATPase (MF1) is inactivated by 5'-p-fluorosulfonylbenzoylethenoadenosine (FSB epsilon A) with pseudo-first order kinetics. The dependence of the rate of inactivation on the concentration of FSB epsilon A revealed an apparent Kd of 0.25 mM. ATP and ADP, and to a lesser extent, ITP and IDP provide partial protection against inactivation by the reagent. Isolation and sequence analysis of major radioactive fragments in peptic or cyanogen bromide digests of MF1 inactivated with [3H]FSB epsilon A indicate that modification of Tyr-alpha 244 is associated with the loss of activity observed. Assessment of the amount of Tyr-alpha 244 derivatized with [3H]FSB epsilon A at specific points during inactivation of the ATPase indicates that maximal inactivation is achieved on modification of this residue in slightly greater than one copy of the alpha subunit. The following characteristics of inactivation of MF1 by FSB epsilon A have also been determined. (a) The rate of inactivation of ITPase activity by FSB epsilon A is 1.4 times greater than that observed for inactivation of ATPase activity under identical conditions. (b) After maximally inactivating the capacity of MF1 to hydrolyze saturating ATP with FSB epsilon A, the modified enzyme retained its capacity to hydrolyze substoichiometric ATP. (c) Inactivation of the ATPase by FSB epsilon A is accelerated by Pi. In each of the above characteristics, MF1 modified by FSB epsilon A resembles enzyme inactivated with 5'-p-fluorosulfonylbenzoyladenosine (FSBA) more than it does enzyme inactivated with 5'-p-fluorosulfonylbenzoylinosine (FSBI). Furthermore, prior inactivation of MF1 with FSBA completely prevents labeling of Tyr-alpha 244 with [3H]FSB epsilon A, whereas prior inactivation of the enzyme with FSBI does not. Since a single catalytic site is modified when FSBI inactivates MF1 whereas three noncatalytic sites are modified when it is maximally inactivated with FSBA, it is concluded that FSB epsilon A also modifies noncatalytic sites.
...
PMID:Tyrosine alpha 244 is derivatized when the bovine heart mitochondrial F1-ATPase is inactivated with 5'-p-fluorosulfonylbenzoylethenoadenosine. 213 76

Parathyroid hormone (PTH) has been shown to bind specifically to the beta subunit of the mitochondrial ATPase on nitrocellulose blots. We have now examined this interaction further, using intact mitochondria, submitochondrial particles, and the purified F1 ATPase. With intact mitochondria, 1 microM concentrations of PTH and its biologically active 1-34 fragment activate the ATPase about 3-fold. This effect was reduced to a 1.4-fold activation with 3-34 and 7-34 fragments of the hormone, and oxidized PTH gave no detectable activity. Activation could only be observed below pH 7. PTH had no significant effect on the activity of the purified enzyme or on submitochondrial particles. However, specific binding of an iodinated PTH analog, [Nle 8,18-Tyr 34] bPTH (1-34) amide, was found with submitochondrial particles and the purified ATPase. Binding affinity with the purified enzyme was about 10(-3) that of the plasma membrane receptor, and the molar stoichiometry was close to 1:1 (PTH:intact enzyme). With submitochondrial particles the affinity was about 10-fold higher than with the purified enzyme. This binding was further examined with PTH derivatives and fragments, and compared to that seen in the plasma membrane receptor. Oxidation of methionine 18 in PTH reduced the affinity about 50%, oxidation of methionine 8 reduced the affinity 95%, and oxidation of both methionines further decreased affinity in both membranes and submitochondrial particles. However, when compared to the native hormone, the 3-34 and 7-34 PTH fragments had much higher affinity for the submitochondrial particles than for the plasma membranes. PTH also reduced chemical crosslinking of the ATP analog, p-fluorosulfonyl benzoyl 5'-adenosine, to the alpha subunit of this enzyme, but did not alter labeling of the enzyme with 3'-O-(4'-benzoyl) benzoyl ATP, suggesting that the hormone binds near a regulatory nucleotide binding site. Direct chemical crosslinking of PTH to the beta-subunit of the enzyme was attained with a cleavable, photoactivate crosslinker, sulfosuccinimidyl 2-(p-azidosalicylamido) ethyl-1,3-dithiopropionate. The crosslinked protein was cleaved with cyanogen bromide and the labeled fragments were sequenced. The labeled fragments were found to be segments of the protein which have previously been implicated as being close to the noncatalytic ATP binding sites.
...
PMID:Characterization of the interaction of parathyroid hormone with the mitochondrial ATPase. 214 4

The degradation of insulin in isolated liver endosomes and the relationships of this process with ATP-dependent endosomal acidification have been studied. Incubation of endosomal fractions containing 125I-insulin in isotonic KCl at 30 degrees C resulted in a rapid loss of insulin integrity as judged from trichloroacetic acid precipitability, Sephadex G-50 chromatography, immunoreactivity and receptor binding ability, with a maximum at pH 5-6 (t1/2: 10, 10, 6 and 6 min, respectively). On a log/log plot, the amount of acid-soluble products generated was linearly related to the amount of insulin associated with endosomes (slope, 0.80). Upon incubation, virtually all acid-soluble products diffused out of endosomes as judged from their solubility in aqueous poly(ethyleneglycol). In permeabilized endosomes, intact insulin was also released in part extraluminally, but only when degradation was inhibited did this release increase with lowering pH. ATP shifted the pH for maximal insulin degradation to about 7.5-8.5 and caused endosomal acidification as judged from the uptake of acridine orange and the fluorescence of internalized fluorescein-labeled dextran and galactosylated bovine serum albumin (delta pH about 0.8-0.9). GTP, ITP and UTP exerted comparable effects but with lower potencies. The ability of ATP to alter the pH dependence of insulin degradation was maximal in the presence of Cl-, other anions being less effective (Br- greater than gluconate = SO4(2-) greater than NO3- = sucrose = mannitol) and/or inhibitory (NO3-). Na+, K+ and Li+ supported more effectively ATP-dependent insulin degradation than did choline. Divalent cations were required for the ATP effect (Mg2+ = Mn2+ greater than Co2+ greater than Ni2+ = Zn2 greater than Ca2+). Little or no effects of ATP occurred in the presence of proton ionophores such as monensin and carbonyl cyanide chlorophenylhydrazone, and inhibitors of the proton ATPase such as N-ethylmaleimide. The abilities of nucleotides, ions and inhibitors to support or inhibit ATP-dependent insulin degradation were well correlated with their abilities to affect ATP-dependent acidification. The acidotropic agents chloroquine and quinacrine caused a leftward shift in the pH dependence of insulin degradation and a decrease in maximal degradation; in the presence of ATP, chloroquine almost completely inhibited degradation at pH 5-9. It is concluded that ATP-dependent acidification, in part by enhancing the dissociation of the insulin-receptor complex, is required for optimum degradation of insulin within liver endosomes.
...
PMID:Degradation of insulin in isolated liver endosomes is functionally linked to ATP-dependent endosomal acidification. 214 19

Akazara scallop troponin-I of Mr 52,000 (52K) was cleaved into two fragments of 17K and 35K with cyanogen bromide. The 17K fragment, along with tropomyosin, inhibited weakly the rabbit actomyosin Mg-ATPase activity, however, the 35K fragment did not affect it at all. In the presence of Akazara scallop TnT (40K component), the 17K fragment, in turn, strongly inhibited the activity, while the 35K fragment did not. The amino acid composition and partial amino acid sequence suggested that the 17K and 35K fragments were derived from C- and N-terminal regions of the TnI, respectively, and that structural similarity to TnIs from other animals is present in the 17K region.
...
PMID:Cyanogen bromide fragments of Akazara scallop Mr 52,000 troponin-I. 214 52

A well-characterized chicken osteoclast plasma membrane vesicle preparation manifested Mg2(+)-dependent ATP hydrolyzing activity of 0.213 mumol inorganic phosphate released per mg protein per minute (n = 7). The Mg2+ dependence showed a high-affinity component with a KMg of 1.293 microM and Vmax of 0.063 mumol Pi per mg protein per minute, and a low-affinity component with a KMg of 297.6 microM and a Vmax of 0.232 mumol Pi per mg protein per minute. The Mg2(+)-ATPase activity was inhibited by N,N'-dicyclohexylcarbodiimide (DCCD, 0.2 mM, 50.7%), N-ethylmaleimide (0.5 mM, 34.6%), nolinium bromide (1 mM, 29.9%), 4,4'-diisothiocyano-2,2'-stilbene sulfonic acid (DIDS, 1 mM, 45.1%), and p-chloromercuribenzoic acid (PCMB, 0.1 mM, 33.8%). Sodium orthovanadate (Na3 VO4) at 1 microM had no effect but caused 29.5% inhibition at 1 mM. Na+ could substitute for K+ without loss of activity, NO3- caused 19.5% inhibition when substituted for Cl-, and acetate replacement of Cl- resulted in 36.4% stimulation of Mg2(+)-ATPase. ATP, GTP, ITP, CTP, and ADP were all hydrolyzed effectively. DCCD (0.2 mM), NEM (0.5 mM), nolinium bromide (1 mM), and DIDS (50 microM) almost completely abolished proton transport as measured spectrofluorometrically by acridine orange quenching. Na3 VO4 (1 mM) had no effect, and duramycin (80 micrograms/ml) inhibited transport 52.7%. K+ replacement of Na+ caused a 79.2% increase in initial proton transport rate. NO3- and acetate substitution of Cl- resulted in a 46.1 and 55.7% decrease in transport, respectively. ATP supports transport far more effectively than the other nucleotides tested. ADP was ineffective. Experiments using the potassium ionophore, valinomycin, indicated that the proton pump functions electrogenically, with Cl- most likely cotransported by an anion transporter. The proton pump also seems to have at least one anion-sensitive site, elucidated by experiments in the presence of NO3- and Cl-.
...
PMID:Biochemical characterization of an electrogenic vacuolar proton pump in purified chicken osteoclast plasma membrane vesicles. 216 21

The cross-linking of the F-actin-caldesmon complex with 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide in the presence of N-hydroxysuccinimide generated four major adducts which were identified on polyacrylamide gels. By cross-linking 3H-actin to 14C-caldesmon, these were found to represent 1:1 cross-linked complexes of actin and caldesmon displaying different electrophoretic mobilities. Tropomyosin did not noticeably affect the cross-linking process. The same four fluorescent species resulting from the cross-linking of caldesmon to F-actin labeled with N-[7-(dimethylamino)-4-methyl-3-coumarinyl]maleimide were subjected separately to partial cleavages with hydroxylamine or cyanogen bromide. These treatments yielded fluorescent 41- and 37-kDa fragments, respectively, from each cross-linked entity indicating unambiguously that caldesmon was cross-linked only to the NH2-terminal actin stretch of residues 1-12. This region is also known to serve for the carbodiimide-mediated cross-linking of the myosin subfragment-1 heavy chain (Sutoh, K. (1982) Biochemistry 21, 3654-3661). A covalent caldesmon-F-actin conjugate containing a protein molar ratio close to 1:19 was isolated following dissociation of uncross-linked caldesmon. It showed a low level of activation of the ATPase activity of skeletal myosin subfragment-1, and the binding of Ca2(+)-calmodulin to the derivative did not cause the reversal of the ATPase inhibition. In contrast, the reversible binding of caldesmon to F-actin cross-linked to myosin subfragment-1 did not inhibit the accelerated ATPase of the complex. The overall data point to the dual involvement of the actin's NH2 terminus in the inhibitory binding of caldesmon and in actomyosin interactions in the presence of ATP.
...
PMID:Cross-linking of smooth muscle caldesmon to the NH2-terminal region of skeletal F-actin. 229 47

The apical membrane of the rabbit corneal endothelium contains a potassium-selective ionic channel. In patch-clamp recordings, the probability of finding the channel in the open state (Po) depends on the presence of either HCO3- or Cl- in the bathing medium. In a methane sulfonate-containing bath, Po is less than 0.05 at all physiologically relevant transmembrane voltages. With 0 mM [HCO3-]o at +60 mV, Po was 0.085 and increased to 0.40 when [HCO3-]o was 15 mM. With 4 mM [Cl-]o at +60 mV, Po was 0.083 and with 150 mM Cl-, Po increased to 0.36. Low Po's are also found when propionate, sulphate, bromide, and nitrate are the primary bath anions. The mechanism of action of the anion-stimulated K+ channel gating is not yet known, but a direct action of pH seems unlikely. The alkalinization of cytoplasm associated with the addition of 10 mM (NH4)2SO4 to the bath and the acidification accompanying its removal do not result in channel activation nor does the use of Nigericin to equilibrate intracellular pH with that of the bath over the pH range of 6.8 to 7.8. Channel gating also is not affected by bathing the internal surface of the patch with cAMP, cGMP, GTP-gamma-s, Mg2+ or ATP. Blockers of Na/H+ exchange, Na(+)-HCO3- cotransport, Na(+)-K+ ATPase and carbonic anhydrase do not block the HCO3- stimulation of Po. Several of the properties of the channel could explain some of the previously reported voltage changes that occur in corneal endothelial cells stimulated by extracellular anions.
...
PMID:Potassium channel in rabbit corneal endothelium activated by external anions. 231 91

The experiments on edible frogs have revealed the relationship between the effect of sodium chloride, skin potential difference and micro-components iodide and bromide present in the solution. The results obtained furnish the additional information on the synergistic action of mineral water iodide and bromide on the body. Iodide ions were found to act mainly through inhibition of sodium channels of cellular membranes, while bromide ions are likely to affect Na, K-ATPase.
...
PMID:[The cellular mechanisms of the physiological action of iodobromide mineral waters]. 233 25


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

---