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)

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

The NAD-dependent glutamate dehydrogenase from Candida utilis was isolated from 32P-labeled cells following enzyme inactivation promoted by glutamate starvation and found to exist in a phosphorylated form. Analysis of purified, fully active NAD-dependent glutamate dehydrogenase (a form) and inactive NAD-dependent glutamate dehydrogenase (b form) for alkalilabile phosphate revealed that the a form contained 0.09 +/- 0.06 mol of phosphate/mol of enzyme subunit and b form 1.25 +/- 0.06 mol of phosphate/mol of enzyme subunit. Phosphorylation caused a 10-fold reduction in enzyme specific activity. Dephosphorylation (release of 32P) and enzyme reactivation occurred on incubation with cell-free yeast extracts, indicating the presence of a phosphoprotein phosphatase in such preparations.
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PMID:Phosphorylation of NAD-dependent glutamate dehydrogenase from yeast. 20 32

We have shown that an acidic phosphoprotein phosphatase (APP-ase) has a different pattern of postnatal maturation in the spleen, thymus and liver of rats and mice. The APP-ase activity increases during the first eight months of postnatal life in the spleen of rats (when it attains an 8--10 times higher value than at birth) and up to the sixth month of life in the spleen of mice. It increases considerably during the first two weeks of postnatal life in the thymus of rats and mice; in the liver of rats it reaches maximum activity before birth, but continues to increase up to the sixth month of postnatal life in the liver of mice. The results show also that the APP-ase from the spleen, thymus and liver of rats is equally active in dephosphorylating ATP and phenyl phosphate during the whole life span of rats, but not in relation to beta-glycerol phosphate. After analyzing its substrate specificity, its pH dependence in relation to different substrates, its kinetic properties, as well as its behaviour towards ascorbic acid and different inhibitors (sodium tungstate and sodium molybdate, L-tartrate, L-phenylalanine and L-cysteine) we have come to the conclusion that the rat spleen APP-ase is different from "nonspecific" acid and alkaline phosphatases and very similar to the EC 3.1.3.16 acid phosphoprotein phosphatase.
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PMID:The ontogenetic evolution of acidic phosphoprotein phosphatase activity in the lymphatic tissue and the liver of the rat. 21 22

The phosphorylation of Ser-32, in addition to Ser-36 of H2B histone, stimulated the rate of Pi release from Ser-36 by the small form (Mr 31 000) of pig heart phosphoprotein phosphatase both in the absence and presence of 50 mM magnesium acetate. By phosphorylation at Ser-32, the Km value for Ser-36 phosphate in H2B histone was increased from 0.38 microM to 1.16 microM in the absence of magnesium acetate, but not significantly changed (from 37.4 microM to 26.2 microM) in the presence of magnesium acetate. With the large form (Mr 224000) of the phosphoprotein phosphatase, however, the phosphorylation at Ser-32 suppressed the rate of Pi release from Ser-36 both in the absence and presence of magnesium acetate. The Km value of the large form for Ser-36 phosphatase in H2B histone was nevertheless increased by phosphorylation at Ser-32, from 1.2 microM to 5.3 microM in the presence of magnesium acetate, but not changed (from 0.26 microM to 0.23 microM) in the absence of magnesium acetate.
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PMID:The control of phosphoprotein phosphatase by the second-site phosphorylation of a substrate. Studies with H2B histone as model substrate. 22 81

When myofibrils from rat hearts were dissolved in concentrated salt solutions and reprecipitated by dilution, they contained both protein kinase (partly cyclic 3':5'-AMP-dependent) and protein phosphatase activities. Troponin-I was the major protein to be phosphorylated by the endogenous myofibril-associated kinase and by added protein kinase. Approximately 1 mole of phosphate per mole of troponin-I was incorporated from radioactive ATP, but the extent of troponin-I phosphorylation could be varied experimentally. An inverse correlation was found between protein phosphorylation and the maximum Ca2+-stimulated myofibrillar Mg2+-ATPase activity, while the amout of calcium required for half-maximum activation was proportional to the extent of protein phosphorylation. The changes in Mg2+-ATPase activity produced in vitro by protein phosphorylation were reproduced in isolated perfused rat hearts treated for short periods with L-noradrenaline (10(-6)M). The changes in myofibrillar function brought about as the result of the phosphorlyation by cAMP-dependent protein kinase suggest that the contractile response is desensitized in order to cope with the rise in intracellular Ca2+ which results from the action of catecholamines on cardiac ventricular cells.
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PMID:Cardiac myofibrillar phosphorylation and adenosine triphosphatase activity. 22 75

A metal-ion-independent, nonspecific phosphoprotein phosphatase (Mr = 35000) which represents the major phosphorylase phosphatase activity in bovine adrenal cortex has been purified to apparent homogeneity. An alkaline phosphatase activity (p-nitrophenyl phosphate as a substrate) of the same molecular weight, which requires both a metal ion (Mg2+ greater than Mn2+ greater than Co2+) and a sulfhydryl compound for activity, has been found to co-purify with the phosphoprotein phosphatase throughout the purification procedures. Characterization of the phosphoprotein and the alkaline phosphatase activities with respect to their catalytic properties, substrate and metal ion specificities, relationship with large molecular forms of the enzymes and responses to various effectors has been carried out. The results indicate that the phosphoprotein phosphatase can be converted by pyrophosphoryl compounds (e.g. PPi and ATP) to a metal-ion-dependent form which, subsequently, can be reactivated by Co2+ greater than Mn2+ but not by Mg2+ or Zn2+. The results also indicate that, although the phosphoprotein and the alkaline phosphatase activities are closely associated, they exhibit distinct physical and catalytic properties. Discussions concerning whether these two activities represent two different forms of the same protein or two different yet very similar polypeptide chains have been presented.
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PMID:Purification and properties of a phosphorylase (phosphoprotein) phosphatase associated with an alkaline phosphatase of Mr 35000 from bovine adrenal cortex. 23 Sep 63

Highly purified Sendai virus contained a protein kinase activity which atatlysed the phosphorylation of endogenous polypeptides or exogenous protamine sulphate. The virus contained very low levels of phosphoprotein phosphatase activity. Polyacrylamide gel analysis of the reaction product indicated that the phosphorylation was specific for certain polypeptides and varied according to whether the virus was grown in eggs or in tissue culture. This variation was partially associated with the difference in the polypeptide pattern that occurred when the virus was grown in eggs or in tissue culture. Characterization of these phosphoproteins demonstrated that the phosphate was incorporated predominantly in a phosphoester linkage with theonine residues. Using a detergent and high salt solubilization procedure, the protein kinase activity was found associated within glycoprotein free virus particles but not with the nucleocapsid-associated polypeptides. In vivo phosphorylation occurred when Sendai virus was grown in eggs or in tissue culture with [32P] and the phosphorylated polypeptides were similar to those of the protein kinase reaction product. Phosphorylation could also be detected in the infected cell and could occur once the virus particle polypeptides were being synthesized. The non-structural polypeptides were not phosphorylated.
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PMID:The phosphorylation of sendai virus proteins by a virus particle-associated protein kinase. 23 97

Callus calcifying cartilage alkaline phosphatase was resolved by DEAE-cellulose column chromatography into two distinct phsophatase activities. The phosphatase activity which was eluted first from the column, (phosphatase I), was active towards a variety of phosphate esters, sodium pyrophosphatase and several linear polyphosphates, while the second phosphatase activity , (phosphatase II), was active toward simple phosphate esters but not towards sodium pyrophosphate and linear oligo or polyphosphates. All the phosphate esters, sodium pyrophosphate and polyphosphates at higher concentrations were inhibitory for phosphatase I. The modulating effects of magnesium, calcium, zinc and other phosphatase modulators have been investigated. Both phosphatases from callus calcifying cartilage were found to be substrates of neuraminidase with sialic acid as the product. Besides the difference in their specificity, the phosphatases were found to be immunologically different and to have different molecular weights, strong indication that they are different enzymes.
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PMID:Resolution, purification and characterization of the orthophosphate releasing activities from fracture callus calcifying cartilage. 23 99

A phosphoprotein phosphatase which is active against chemically phosphorylated protamine has been purified about 500-fold from bovine adrenal cortex. The enzyme has a pH optimum between 7.5 and 8.0, and has an apparent Km for phosphoprotamine of about 50 muM. The hydrolysis of phosphoprotamine is stimulated by salt, and by Mn2+. Hydrolysis of phosphoprotamine is inhibited by ATP, ADP, AMP, and Pi, but is not affected by AMP or cyclic GMP. The purified phosphoprotein phosphatase preparation also dephosphorylates p-nitrophenyl phosphate and phosphohistone, and catalyzes the inactivation of liver phosphorylase, the inactivation of muscle phosphorylase a (and its conversion to phosphorylase b), and the inactivation of muscle phosphorylase b kinase. Phosphatase activities against phosphoprotamine and muscle phosphorylase a copurify over the last three stages of purification. Phosphoprotamine inhibits phosphorylase phosphatase activity, and muscle phosphorylase a inhibits the dephosphorylation of phosphoprotamine. These results suggest that one enzyme possesses both phosphoprotamine phosphatase and phosphorylase phosphatase activities. The stimulation of phosphorylase phosphatase activity, but not of phosphoprotamine phosphatase activity, by caffeine and by glucose, suggests that the different activities of this phosphoprotein phosphatase may be regulated separately.
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PMID:Purification and characterization of a phosphoprotein phosphatase from bovine adrenal cortex. 24 3

Glycogen synthase b was purified from rabbit liver by a procedure involving isolation of the glycogen-enzyme complex, DEAE-cellulose chromatography, and affinity chromatography. The purified enzyme had a specific activity of 25 mumol of glucose transferred from UDPglucose into glycogen per min per mg of protein at 30 degrees C in the presence of 10 mM glucose 6-P, and appeared to be homogeneous by the criterion of polyacrylamide disc gel electrophoresis. The b form was convertible into the a form by a rabbit-liver protein phosphatase. A subunit size of 85 000 was determined by electrophoresis in sodium dodecyl sulfate and molecular weights of 183 000 +/- 20 000 and 170 000 +/- 21 000 were determined for the a and b forms of the enzyme, respectively. On conversion of the a into the b form, 1.13 mol of phosphate was incorporated per 85 000 g of protein. The degree of phosphorylation and loss of glycogen synthase a activity paralleled each other.
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PMID:Purification and properties of rabbit-liver glycogen synthase. 81 26


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