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 (Ca(2+)+Mg2+)-ATPase of the plasma membrane is activated by negatively charged phospholipids. The mechanism of this activation was investigated by studying the effect of negatively charged phospholipids on the steady-state phosphointermediate level and on the p-nitrophenylphosphatase activity. Both parameters were differentially affected by different acidic phospholipids. The level of phosphoprotein intermediate was not affected by phosphatidylserine (20% of total phospholipid), but it was increased by 60% by phosphatidylinositol 4-phosphate. Phosphatidylserine increased the p-nitrophenylphosphatase activity, whereas phosphatidylinositol 4-phosphate had no significant effect. It is suggested that phosphatidylinositol 4-phosphate mainly affects a reaction step which leads to accelerated formation of the phosphointermediate, whereas the action of phosphatidylserine would affect two reaction steps, one upstream and one downstream of the phosphointermediate.
...
PMID:Stimulation of the catalytic cycle of the Ca2+ pump of porcine plasma-membranes by negatively charged phospholipids. 131 67

8-Methoxy-4-[(2-isopropylphenyl)amino]-3-quinolinecarboxylate ethyl ester (AHR-9294) inhibited acid secretion stimulated by histamine, pentagastrin or carbachol in rats, and by histamine or feeding in dogs. AHR-9294 was about half as potent as omeprazole and exhibited a shorter duration of action. Based on its inhibition of acid secretion induced by different secretagogues and its lack of effect on histamine-stimulated adenylate cyclase activity, AHR-9294 does not appear to operate at the histamine receptor or adenylate cyclase. Rather, studies on enriched oxyntic microsomal preparations showed AHR-9294 to be an effective inhibitor of the H+ pump enzyme, H,K-ATPase, suggesting this might be the site of antisecretory activity. Kinetic studies revealed that inhibition of both K(+)-activated ATPase and p-nitrophenylphosphatase by AHR-9294 was purely competitive with K+ and its congeners, indicating that AHR-9294 and its analogs belong to the class of compounds known as "K+)-site" inhibitors. On the other hand, inhibition by AHR-9294 was noncompetitive with both ATP and p-nitrophenylphosphatase on their respective rates of hydrolysis (i.e., both Vmax and the apparent Km were reduced, but Vmax/Km was unchanged). Studies on partial reactions of the H,K-ATPase showed that the rate of ATP/ADP exchange was unaffected by AHR-9294 and the steady-state level of phosphoenzyme was only partially reduced (thus ATP/enzyme interaction was not affected); however, the rate of K(+)-catalyzed dephosphorylation of phosphoenzyme was markedly decreased.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:AHR-9294: a novel inhibitor of H,K-ATPase antagonizes gastric HCl secretion in vivo. 131 65

Cadmium (Cd) inhibited the activities of Na(+)-K+ ATPase (IC50 = 5.0 x 10(-5) M), K(+)-p-nitrophenyl phosphatase (PNPPase) (IC50 = 4.0 x 10(-5) M) and 3H-ouabain binding (IC50 = 7.5 x 10(-5) M) in rat brain microsomes. Monothiols (cysteine but not glutathione and D-penicillamine) and dithiols (dimercaprol, dimercaptosuccinic acid and dithiothreitol) offered varied levels of protection against Cd-inhibition of Na(+)-K+ ATPase. Protection of Na(+)-K+ ATPase by these sulfhydryl (SH) agents was higher at 7.5 as compared to 8.5 pH. The present data suggest that Cd-inhibited Na(+)-K+ ATPase, by interfering with phosphorylation of enzyme molecule and dephosphorylation of the enzyme-phosphoryl complex and exerts a similar effect to that of SH-blocking agents.
...
PMID:The effects of cadmium in vitro on adenosine triphosphatase system and protection by thiol reagents in rat brain microsomes. 131 40

1. The tubulovesicles of hog and rabbit gastric parietal cells were immunopurified from microsomes using monoclonal antibodies against the (H+, K+)-ATPase. 2. The best yields of immunoprecipitation were obtained with an ATPase/mAb molar ratio of 0.3: the immunoprecipitate contained 79 and 90% of the hog and rabbit microsomal PNPPase activity respectively and K(+)-stimulated ATPase specific activity was 221 +/- 29 mumoles Pi per hr and per mg of membrane protein. 3. The immunoprecipitate contained vesicles that were 85% cytoplasmic-side out, like tubulovesicles in vivo, demonstrating that the epitopes were cytoplasmic. 4. The alpha-beta protomer of (H+, K+)-ATPase accounted for 80 +/- 12% of the immunopurified proteins. 5. The major other proteins ran at 80, 75, 69, 57, 47, 44, 39, 34 and 32 kDa on the SDS-PAGE. 6. Comparative analysis between sucrose-gradient purified fractions and immunopurified tubulovesicles demonstrated that carbonic anhydrase and actin were contaminants and that the 53 kDa and presumably the 50 kDa bands of the gradient fraction were alpha and beta subunits of F1 ATPase.
...
PMID:Immunopurification of gastric parietal cell tubulovesicles. 131 5

The effects of cassigarol A, a naturally occurring polyphenol, on gastric H+,K(+)-ATPase and gastric acid secretion were studied. Cassigarol A inhibited H+,K(+)-ATPase and K-stimulated p-nitrophenyl phosphatase from hog gastric mucosa with 50% inhibition of 1.2 x 10(-6) and 6.3 x 10(-6) M, respectively. The kinetic study showed that the inhibition of H+,K(+)-ATPase by cassigarol A was competitive with respect to ATP and non-competitive with respect to K+. Cassigarol A inhibited both H+,K(+)-ATPase-mediated proton transport and 2-deoxy-D-glucose-induced acid secretion. On the other hand, cassigarol A acetate, in which phenolic hydroxy groups are acetylated, was not effective in the inhibition of enzyme activity and acid secretion. These results indicate that cassigarol A is a potent inhibitor of gastric H+,K(+)-ATPase, that the anti-secretory activity of cassigarol A is related to the inhibition of H+,K(+)-ATPase and that an important moiety of cassigarol A in the interaction with the enzyme is the phenolic hydroxy groups.
...
PMID:Inhibition of gastric H+,K(+)-ATPase and acid secretion by cassigarol A, a polyphenol from Cassia garrettiana Craib. 132 29

The effect of tannic acid on gastric H+,K(+)-ATPase was studied. Tannic acid dose-dependently inhibited pig gastric H+,K(+)-ATPase activity with an IC50 value of 2.9 x 10(-8) M. Tannic acid also inhibited K(+)-stimulated p-nitrophenyl phosphatase (K(+)-pNPPase) activity, which is found in gastric H+,K(+)-ATPase preparations, as well as H+,K(+)-ATPase activity, with an IC50 value of 4.1 x 10(-7) M. Kinetic studies showed that the inhibition of H+,K(+)-ATPase activity by tannic acid was competitive with respect to ATP and noncompetitive with respect to K+. These results show that tannic acid is a potent inhibitor of gastric H+,K(+)-ATPase; this may be related to its anti-secretory and anti-ulcerogenic effects.
...
PMID:Inhibitory effect of tannic acid on gastric H+,K(+)-ATPase. 132 83

The effects of the cholinergic agonist carbachol (Cch) and guanine nucleotides on the Na,K-ATPase and K-dependent p-nitrophenylphosphatase (K-p-NPPase) activities in rabbit and dog myocardial sarcolemma vesicles in the presence of the pore-forming antibiotic alamethicin (20 micrograms/ml), was studied. Cch (0.01-100 microM) inhibited the both enzymatic activities by 40-45% (IC50 = 0.3-0.5 microM) only after addition of GTP (50 microM) or its analogs: GTP gamma S (0.1-1.0 microM) and Gpp(NH)p (10 microM). The muscarinic acetylcholine receptor (mAchR) antagonist atropine (10 microM) blocked the effect of Cch. GTP gamma S alone produced a concentration-dependent decrease in the both Na,K-ATPase and K-p-NPPase activities by 40-45% (IC50 = 1-2 microM) with a lag period of about 3 minutes; this lag disappeared in the presence of the agonist. The GDP analog GDP beta S (0.01-100 microM) neither affected these activities nor promoted the inhibiting effect of Cch. Pretreatment of sarcolemmal vesicles with 20 micrograms/ml of pertussis toxin in the presence of 100 microM NAD abolished the inhibiting effect of Cch on the Na,K-ATPase and phosphatase activities. Under these conditions pertussis toxin catalyzed the ADP-ribosylation of alpha-subunits of the inhibitory GTP-binding protein (G1) which were identified immunochemically as alpha i2, alpha i3 and, possibly, alpha i1. The data obtained testify to the involvement of G1 in the mAchR-mediated inhibition of myocardial sarcolemmal Na,K-ATPase as well as in the signal transduction from the receptor to the enzyme.
...
PMID:[The role of a GTP-binding protein in coupling of a muscarinic cholinergic receptor and Na,K-ATPase in myocardial sarcolemma]. 132 37

The cytochemical demonstration of the atrial cardiac myocyte pumping activity has been made by detecting p-nitrophenylphosphatase (NPPase), which is used by investigating of Na(+)-K(+)-ATPase and H(+)-K(+)-ATPase activities. The fine ultrastructural localization of these enzymes was studied using cytochemical methods with cerium as a capturing agent. Na(+)-K(+)-ATPase was localized on the atrial muscle cell plasma membrane, T-tubule membrane, endothelial cell nuclear membrane, and cardiac myocyte nuclear membrane. H(+)-K(+)-ATPase was localized on the atrial muscle cells plasma membrane, T-tubule membrane, and sarcoplasmatic reticulum. The present findings indicate that the transporting metabolic activity of the heart as an endocrine organ is realized by the interaction between p-NPPases.
...
PMID:Cytochemical investigation of p-NPPase activity in rat cardiac muscle. 132 34

The effect of beta-eudesmol, one of the major components in So-jutsu (Atractylodis Lanceae Rhizoma), on K(+)-dependent p-nitrophenyl phosphatase (K(+)-pNPPase) activity was studied. It inhibited K(+)-pNPPase activity with an I50 value of 4.1 x 10(-4) M. The inhibition rate decreased as the K+ concentration was increased, whereas greater inhibition was observed with high concentrations of either Na+ or ATP. The Ki values for Na+ in the presence of 0, 0.1 and 1 mM ATP were 140, 260 and 310 mM, respectively, but with the addition of beta-eudesmol, these values decreased to 90 mM regardless of the ATP concentration. This study on K(+)-pNPPase activity supports the conclusion obtained from the study on Na+,K(+)-ATPase activity (Satoh K et al., Biochem Pharmacol 44: 373-378, 1992) that is, beta-eudesmol interacts with enzyme in the Na.E1 form and inhibits the reaction step Na.E1----Na.E1-P. Furthermore, in the study of the effects of K+ and beta-eudesmol on K(+)-pNPPase activity, it was confirmed that beta-eudesmol prevents the conformational change of Na.E1----K.E2.
...
PMID:Interaction of beta-eudesmol with Na+,K(+)-ATPase: inhibition of K(+)-pNPPase activity. 132 67

We have utilized cobalt-reaction technique for histochemical and cytochemical demonstration of ouabain-sensitive, K(+)-dependent p-NPPase (Na(+)-K(+)-ATPase). The incubation medium consisted of: cobalt chloride, tricine buffer, p-nitrophenylphosphate, KCl, and phenylalanine. Final pH 7.4. Ultracytochemically, reaction products were localized along the internal side of sarcolemma and its vesicles, T-tubule membrane, and capillary endothelial cells. These results suggest that the method is reliable and can be used to investigate the localization of Na(+)-K(+)-ATPase activity.
...
PMID:Demonstration of ouabain-sensitive, potassium-dependent p-nitrophenylphosphatase activity in the rat cardiac muscle by cobalt-based cytochemistry. 132


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

---