Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.1 (Mg2+-ATPase)
 1,484 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The phospholipid and fatty acid composition and role of phospholipids in enzyme and transport function of gastric (H+ + K+)-ATPase vesicles was studied using phospholipase A2 (bee venom). The composition (%) was phosphatidyl-choline (PC) 33%; sphingomyelin (sph) 25%; phosphatidylethanolamine (PE) 22%; phosphatidylserine (PS) 11%; and phosphatidylinositol (PI) 8%. The fatty acid composition showed a high degree of unsaturation. In both fresh and lyophilized preparations, even with prolonged incubation, only 50% of phospholipids were hydrolyzed, but the amount of PE and PS disappearing was increased following lyophilization. There was a marked decrease in K+-ATPase activity (75%) but essentially no loss of the associated K+ p-nitrophenyl phosphatase was found. ATPase activity could be largely restored by various phospholipids (PE greater than PC greater than PS). There was also an increase in Mg2+-ATPase activity, partially reversed in fresh preparations by the addition of phospholipids (PE greater than PS greater than PC). Proton transport activity of the preparation was rapidly inhibited, initially due to a large increase in the HCl permeability of the preparation. Associated with these enzymatic and functional changes, the ATP-induced conformational changes, as indicated by circular dichroism spectra were inhibited.
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PMID:Effect of phospholipase A2 on purified gastric vesicles. 4 34

Actin modified at Lys-61 with fluorescein 5-isothiocyanate (FITC) recovers the ability to polymerize following the binding of phalloidin. The resulting polymer (FITC-P-actin) activates the S1-Mg2+-ATPase activity to the same extent as non-labeled F-actin. However, in the absence of phalloidin, FITC-actin (0.5 mg/ml) neither polymerized nor activated the S1-Mg2+-ATPase activity effectively even when it was preincubated with S1 for 3 h in 0.1 mM ATP, 0.1 mM CaCl2, and 1 mM Tris/HCl (pH 8.0), in contrast to the previous report [Miller, L., Phillips, M., & Reisler, E. (1988) Eur. J. Biochem. 174, 23-29]. The modification of Lys-61 did not impair the ability to bind tropomyosin or tropomyosin-troponin. On the other hand, the fluorescence polarization of FITC-P-actin increased when tropomyosin or troponin-tropomyosin was added. Moreover, the modification of Lys-61 affected the regulation of the actin activation of the S1-Mg2+-ATPase activity by the tropomyosin and troponin complex. In 30 mM KCl, 2.5 mM ATP, and 5 mM MgCl2, tropomyosin alone has been shown to inhibit the actin-activated S1-Mg2+-ATPase. This inhibition did not occur with FITC-P-actin even though tropomyosin was tightly bound. When troponin-tropomyosin was added, the FITC-P-actin activation of S1-Mg2+-ATPase activity was regulated in response to micromolar Ca2+ concentrations. On the other hand, in 30 mM KCl, 2.5 mM ATP, and 2 mM MgCl2, tropomyosin alone did not inhibit the actin-activated S1-Mg2+-ATPase activity with either non-labeled F-actin or FITC-actin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Interaction of Lys-61 labeled actin with myosin subfragment-1 and the regulatory proteins. 253 48

The effects of chloroquine on calmodulin (CaM)-related enzyme activities and the shape of human erythrocytes have been studied. It was found that the CaM activation of rat brain phosphodiesterase was abolished by the addition of chloroquine. CaM was included in the assay of phosphodiesterase activity at the concentration that gave half-maximal activation. The concentration of chloroquine that caused 50% inhibition of CaM stimulation of phosphodiesterase was 7 X 10(-5)M. The type of inhibition was competitive with respect to CaM. The CaM-stimulated Ca2+, Mg2+-ATPase in erythrocyte membrane was also inhibited by chloroquine, the 50% inhibitory concentration of which was about 2 X 10(-4)M. Its mode of action was also competitive with respect to CaM. The shapes of erythrocyte ghosts prepared by hypotonic hemolysis were examined in a solution consisting of 2 mM MgCl2, 154 mM NaCl and 10 mM Tris-HCl (pH 7.4); they were discocytic in the presence of 2 mM ATP and in its absence. They were converted to the invaginated form by the addition of chloroquine in the concentration range of 1 X 10(-4)-5 X 10(-4)M. This concentration is similar to that which caused the inhibition of CaM activation of Ca2+, Mg2+-ATPase.
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PMID:Inhibition of calmodulin stimulation of phosphodiesterase and Ca2+, Mg2+-ATPase activities and shape change of erythrocyte ghosts by chloroquine. 296 Mar 25

Erythrocyte membranes, isolated after step-wise hemolysis in buffered sucrose (Tris-sucrose membranes), showed higher Ca2+ Mg2+-ATPase activity than erythrocyte membranes obtained after hemolysis in Tris-HCl, and washing in EDTA (Tris-EDTA membranes). In Tris-sucrose membranes, the activity was not stimulated by the addition of monovalent cations, or calmodulin. Differences reported for the activity and properties of Ca2+ Mg2+-ATPase between Tris-EDTA membranes of Duchenne patients and controls, were not found in Tris-sucrose membranes. Also the activity and properties of the Ca2+-pump in resealed erythrocyte membranes were not changed.
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PMID:Ca2+ transport in erythrocytes from patients with Duchenne muscular dystrophy. 613 95