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:3.1.3.16 (calcineurin)
17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A density gradient-purified microsomal membrane preparation from rabbit fundic gastric mucosa was used for a detailed study of the K+-stimulated ATPase and associated intermediate reactions. Membranes incubated with gamma-[32P]ATP show the rapid incorporation of 32P into phosphoprotein. Phosphoprotein levels were markedly reduced (1) when ATP hydrolysis went to completion or (2) upon addition of unlabeled ATP, thus suggesting the participation of a rapid turnover phosphorylated intermediate in the gastric microsomal ATPase. Addition of K+, Rb+ or Tl+ greatly reduced the level of the intermediate while stimulating ATPase activity; the observed affinities of these cations were similar for the effects on both ATPase and intermediate levels, with Tl+ greater than K+ greater than Rb+. Neither ATPase nor intermediate were stimulated by Na+, and ouabain was without effect on the reactions, thus differentiating this system from the (Na+ + K+)-ATPase. Addition of various inhibitors showed differential effects on the partial reactions of the gastric ATPase system. N-ethylmaleimide and Zn2+ showed characteristics of completely abolishing the K+-stimulated component of ATPase as well as the effects of K+ in reducing the level of intermediate, thus suggesting that these agents exert their inhibitory effect on a phosphoprotein phosphatase partial reaction. F- abolished the K+-stimulated ATPase, but its more complex effects on the intermediate suggested an additional reaction step within the domain of the phosphorylated intermediate. Results are consistent with a model system for the gastric microsomal ATPase involving a Mg2+-dependent protein kinase, a phosphorylated intermediate(s), and a K+-stimulated phosphoprotein phosphatase.
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PMID:Studies on the phosphorylated intermediates of a K+-stimulated ATPase from rabbit gastric mucosa. 0 43

Plasma membranes have been prepared from porcine thyroid glands using sucrose gradients. The fractions having a density in sucrose of 1.18 g/ml mainly contained plasma membranes and were moderately contaminated with other subcellular components as shown by marker enzyme data. Purified plasma membranes incubated in the presence of [32-P]gamma ATP incorporated 32-P. Kinetics of incorporation of 32-P into endogenous substrates studied in various buffers and with increasing ATP concentration suggest a phosphodephosphorylating system related to cAMP-dependent protein kinase and phosphoprotein phosphatase activities. The two enzymatic activities associated with plasma membranes have been demonstrated using exogenous substrates. cAMP increases and fluoride ions decrease the extent of membrane phosphorylation. The specific activity of protein kinase was 10-12 times higher than in the initial homogenate and was only slightly enhanced in the presence of 0.5% Nonidet as compared to microsomal fraction. cAMP binding to membrane proteins was 3 times higher than to the other particulate fractions. TSH present in the incubating medium or added after 5 min of 32-P labelling induced a rapid stimulation of endogenous phosphorylation followed by a rapid decrease. Phosphorylated membrane substrates were analyzed: high voltage paper electrophoresis after partial hydrolysis indicated that [32-P]phosphate is incorporated into serine and threonine residues as o-phosphate derivatives. SDS-polyacrylamide gel electrophoresis showed several 32--labelled fractions. When enhanced by cAMP, no specific phosphorylation of protein components was observed.
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PMID:Phosphorylation of purified thyroid plasma membranes incubated with [32-P]ATP. 16 13

A protein whose endogenous phosphorylation and dephosphorylation are affected by cAMP has been found in the soluble and particulate fractions of all vertebrate tissues studied. This phosphoprotein, which contained a substantial proportion of the radioactive phosphate observed on SDS-polyacrylamide gels, was estimated to have an apparent molecular weight of 49,000. In the presence of Zn++, cAMP inhibited the endogenous phosphorylation of this protein (protein 49) in the cytosol and microsomal fractions. In the presence of Mg++, cAMP stimulated the phosphorylation of protein 49 in the cytosol fractions, but had only slight effects in the microsomal fractions. The dephosphorylation of protein 49 by an endogenous protein phosphatase was markedly stimulated by cAMP in the cytosol and microsomal fractions of all tissues studied. The binding of 8-azido-cAMP (a photoaffinity analog of cAMP, which reacts specifically with cAMP-binding sites) to subcellular fractions was also studied. This binding was principally to a protein of molecular weight 49,000. These and other data suggest that a cAMP-binding protein with a molecular weight of 49,000 capable of undergoing cAMP-dependent phosphorylation and dephosphorylation, occurs in a variety of tissues.
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PMID:Widespread occurrence of a specific protein in vertebrate tissues and regulation by cyclic AMP of its endogenous phosphorylation and dephosphorylation. 16 55

The present study demonstrated the presence within the myocardium of phosphoprotein phosphatase activity which can account for dephosphorylation of a 22,000 dalton phosphoprotein of cardiac sarcoplasmic reticulum that has been associated with the stimulatory effects of adenosine 3':5'-monophosphate (cyclic AMP)-dependent protein kinase on calcium transport (Tada, M., Kirchberger, M. A., and Katz, A. M. (1975) J. Biol. Chem. 250:2640-2647). Dog cardiac microsomes, consisting mainly of fragmented sarcomplasmic reticulum, were phosphorylated by incubation with cyclic AMP-dependent protein kinase and [gamma-32P]ATP, and subsequently washed with trichloroacetic acid or buffered KCl. Phosphorylated microsomes contained approximately 1 nmole of 32P bound per mg of microsomal protein, 32P labeling occurring almost exclusively at the 22,000 dalton component. Soluble phosphoprotein phosphatases, isolated from the cytosol, catalyzed dephosphorylation of 32P-labeled microsomes. The existence of a phosphoprotein phosphatase that is associated with the microsomes was demonstrated by the ability of the microsomes to dephosphorylate 32P-histone. This membrane-associated phosphatase activity can also account for a rapid decrease in the amount of 32P-labeling of the 22,000 dalton protein. The dephosphorylation of the phosphorylated 22,000 dalton protein by phosphoprotein phosphatase satisfies an important requirement for the phosphorylation of the 22,000 dalton protein to serve a physiological role, namely, its reversibility.
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PMID:Phosphoprotein phosphatase-catalyzed dephosphorylation of the 22,000 dalton phosphoprotein of cardiac sarcoplasmic reticulum. 17 94

1. Calcium transport into microsomal vesicles of respiratory (tracheal) smooth muscle was characterized. This calcium transport was ATP dependent and stimulated by the presence of the oxalate ion. The magnitude of transport was similar to that reported for microsomes from other types of smooth muscle. 2. Bovine and rabbit, heavy and light microsomes were isolated from respiratory (tracheal) and vascular (aortic) smooth muscle. Preincubation of these vesicles with cyclic AMP and protein kinase did not alter the transport of calcium into the vesicles. There uas no evidence of phosphate incorporation into microsomal membrane proteins. Similar results were obtained if phosphorylase b kinase replaced the combination of cyclic AMP and protein kinase during the preincubation. 3. The phosphoprotein phosphatase activity of cardiac sarcoplasmic reticulum and smooth muscle microsomes was determined. The activity of this enzyme was found to be several-fold less in the cardiac sarcoplasmic reticulum than in various smooth muscle microsome preparations.
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PMID:Determination of calcium transport and phosphoprotein phosphatase activity in microsomes from respiratory and vascular smooth muscle. 20 Dec 93

The role of adenosine 3',5'-monophosphate (cyclic AMP)-dependent membrane phosphorylation in the regulation of microsomal calcium transport in rat aortic smooth muscle was studied. Cyclic AMP-dependent protein kinase augmented the phosphorylation of serine residues in a microsomal protein component with a molecular weight of about 44,000 (determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and the majority of 32P incorporation was in serine residue(s). The phosphorylated protein had stability characteristics of a phosphoester. The phosphorylated substrate was not extracted from the trichloroacetic acid (TCA) precipitate with organic solvents or by suspension in hot TCA; and the demonstrated hydroxylamine insensitivity suggested that the substrate was not lipid or nucleic acid. Intrinsic phosphoprotein phosphatase cleaved the labeled phosphate from the cyclic AMP-stimulated microsomes in the first 5 min of incubation. Microsomes phosphorylated in the presence of 1 micron cyclic AMP or 1 micron cyclic AMP plus 0.1 mg/ml protein kinase exhibited enhanced calcium uptake. We suggest that reversible phosphorylation of microsomal membranes may play an important role in the regulation of aortic microsomal calcium transport by cyclic AMP.
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PMID:Role of cyclic AMP in rat aortic microsomal phosphorylation and calcium uptake. 20 57

Cardiac microsomes contained an intrinsic adenosine 3',5'-monophosphate (cyclic AMP)-dependent protein kinase which stimulated phosphorylation of serine residue(s) of microsomal protein. The phosphorylated residues were associated with a microsomal protein component of 20,000 molecular weight as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Intrinsic phosphoprotein phosphatase activity of the microsomal membrane resulted in rapid dephosphorylation of these residues. Microsomes phosphorylated in the presence of cyclic AMP (10(-6) M) exhibited enhanced calcium uptake. We conclude that: 1) cardiac microsomes contain intrinsic cyclic AMP-dependent protein kinase(s) which phosphorylate a specific microsomal protein and phosphoprotein phosphatase(s) capable of dephosphorylating this protein, 2) phosphorylation of this protein enhances calcium uptake, 3) reversible phosphorylation of microsomal membrane may be an important mechanism for the regulation of calcium uptake of cardiac microsomes by cyclic AMP.
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PMID:Characterization of soluble and microsomal adenosine 3',5'-monophosphate-dependent protein kinases from rabbit heart. 24 43

The activity of rat liver 3-hydroxy-3-methylglutaryl-coenzyme A reductase [HMG-CoA reductase; mevalonate:NADP(+) oxidoreductase (CoA-acylating), EC 1.1.1.34] can be modulated in vitro by a phosphorylation-dephosphorylation reaction sequence. A microsomal reductase kinase catalyzes the phosphorylation of HMG-CoA reductase and histones. Histone phosphorylation was enhanced 2- to 3-fold by cyclic AMP. Reductase kinase exists in interconvertible active and inactive forms. Incubation of reductase kinase with phosphoprotein phosphatase resulted in a time-dependent decrease in the ability of reductase kinase to catalyze the phosphorylation of histones and to inactivate HMG-CoA reductase. Incubation of phosphoprotein phosphatase-inactivated reductase kinase with [gamma-(32)P]ATP plus Mg(2+) and a partially purified protein kinase designated reductase kinase kinase resulted in parallel increases in protein-bound (32)P radioactivity and ability to inactivate HMG-CoA reductase. Incubation of (32)P-labeled reductase kinase with phosphoprotein phosphatase resulted in a time-dependent loss of protein-bound (32)P radioactivity and a decrease in the ability to inactivate HMG-CoA reductase. Polyacrylamide gel electrophoresis of purified reductase kinase incubated with reductase kinase kinase and [gamma-(32)P]ATP plus Mg(2+) revealed that the (32)P radioactivity and reductase kinase enzymic activity were located in a single electrophoretic position. Dephosphorylation of (32)P-labeled purified reductase kinase with phosphoprotein phosphatase was associated with significant loss of radioactivity and enzymic activity in the protein band ascribed to reductase kinase. These results provide evidence that the activity of reductase kinase, like HMG-CoA reductase, is modulated by a reversible phosphorylation-dephosphorylation reaction sequence.
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PMID:Characterization and regulation of reductase kinase, a protein kinase that modulates the enzymic activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase. 29 71

About an eightfold increase in protamine kinase activity was detected following extraction of highly purified microsomes from bovine kidney with 1% Triton X-100. Relative to the soluble fraction, the microsomes contained about 30% protamine kinase activity. The microsomal protamine kinase was purified to apparent homogeneity. The purified enzyme exhibited an apparent M(r) approximately 45,000 as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by gel permeation chromatography on Sephacryl S-200. Relative to protamine, the purified kinase exhibited about 100% activity with the synthetic peptide RRLSSLRA and about 5, 8, and less than 0.1% activity with casein, histone H2B, and histone H1, respectively. The purified kinase phosphorylated several 40 S ribosome polypeptides. One of these polypeptides was identified as ribosomal protein S6 by N-terminal sequencing. About 2.5 mol of phosphoryl groups was incorporated per mole of ribosomal protein S6 following incubation of the 40 S ribosomes with the purified kinase. Following incubation with protein phosphatase 2A2, purified preparations of the protamine kinase were inactivated. These properties were identical to those of purified preparations of a protamine kinase from extracts of bovine kidney cytosol (Z. Damuni, G.D. Amick, and T.R. Sneed, 1989, J. Biol. Chem. 264, 6412-6418). Near identical peptide patterns were obtained following incubation of purified preparations of the microsomal and cytosolic protamine kinases with Staphylococcus aureus V8 proteinase. The results indicate that a form of the cytosolic protamine kinase is present in microsomes.
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PMID:Purification and properties of a protamine kinase from bovine kidney microsomes. 132 15

1. Guinea-pig liver contained more phosphorylase in the active (phosphorylated) form and less synthase in the active (dephosphorylated) form when compared with rat liver. 2. Activities of cyclic AMP-dependent protein kinase and Ca(2+)-dependent phosphorylase kinase were the same in rat and guinea-pig livers. 3. Activities of phosphorylase phosphatase and synthase phosphatase in the extract and glycogen plus microsomal fraction of guinea-pig liver were significantly lower than those of rat liver. 4. The existence of inhibitor-1 in the liver of guinea-pig can maintain a lower activity of type-1 protein phosphatase, especially when inhibitor-1 is phosphorylated by cyclic AMP-dependent protein kinase.
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PMID:Comparative characterization of liver glycogen metabolism in rat and guinea-pig. 145 30


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