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)

Cattle brain cortex was homogenised in 0, 29 mol/1 sucrose and centrifuged at 101 000 X g. The supernatant contains the majority of 3 enzymes participating in protein turnover: cathepsin (EC 3.4.4.23), phosphoprotein phosphatase (EC 3.1.3.16) and acid phosphatase (EC 3.1.3.2). They were separated by chromatography on Sephadex G 200 in neutral buffer. The cathepsin was purified up to 380 fold by gel filtration on Sephadex and column electrophoresis. The pH optimum of cathepsin was 5.7. At 37 degrees C no decrease of activity was measurable during 30 min. The Km was found to be 2.75 mg/ml Casein Hammarsten. The molecular weight by gel filtration and exclusion-gel electrophoresis was about 45 000, corresponding to the cathepsin from human liver (Barrett, A.J. (1970) Biochem. J. 117, 601-607). The sedimentation constant 3.0 S20,W is comparable with the values of proteinase of different origin, and the composition is similar with respect to the high proportion of acidic amino acids. The phosphoprotein phosphatase can be further purified by chromatography on hydroxyapatite and by column electrophoresis. The pH optimum of phosphoprotein phosphatase was about pH 5.5. At 45 degrees C no decrease of activity was measurable during 20 min; the Km was 1.43 mg/ml casein isoelectric. The pH optimum of acid phosphatase was about 5.6. At 54 degrees C NO DECREASE OF ACTIVITY WAs measurable during 30 min; the Km was 2 mumol/1 for Sodium phenolphthalein diphosphate. All three enzymes slowly lost their activity during several weeks at - 4 degrees C, apparently by self digestion in the cold.
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PMID:[Cathepsin, phosphoprotein-phosphatase and acid phosphatase in the soluble fraction of the cattle brain cortex: purification and properties (author's transl)]. 0 48

The phosphoprotein phosphatase(s) acting on muscle phosphorylase a was purified from rabbit liver by acid precipitation, high speed centrifugation, chromatography on DEAE-Sephadex A-50, Sephadex G-75, and Sepharose-histone. Enzyme activity was recovered in the final step as two distinct peaks tentatively referred to as phosphoprotein phosphatases I and II. Each phosphatase showed a single broad band when examined by sodium dodecyl sulfate gel electrophoresis; the molecular weights derived by this method were approximately 30,500 for phosphoprotein phosphatase I and 34,000 for phosphoprotein phosphatase II. The s20, w value for each enzyme was 3.40. Using this value and values for the Stokes radii, the molecular weight for each enzyme was calculated to be 34,500. Both phosphatases, in addition to catalyzing the conversion of phosphorylase a to b, also catalyzed the dephosphorylation of glycogen synthase D, activated phosphorylase kinase, phosphorylated histone, phosphorylated casein, and the phosphorylated inhibitory component of troponin (TN-I). The relative activities of the phosphatases with respect to phosphorylase a, glycogen synthase D, histone, and casein remained essentially constant throughout the purification. The activities of both phosphatases with different substrates decreased in parallel when they were denatured by incubation at 55 degrees and 65 degrees. The Km values of phosphoprotein phosphatase I for phosphorylase a, histone, and casein were lower than the values obtained for phosphoprotein phosphatase II. With glycogen synthase D as substrate, each enzyme gave essentially the same Km value. Utilizing either enzyme, it was found that activity toward a given substrate was inhibited competitively by each of the alternative substrates. The results suggest that phosphoprotein phosphatases I and II are each active toward all of the substrates tested.
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PMID:Purification, properties, and substrate specificities of phosphoprotein phosphatase(s) from rabbit liver. 0 49

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

A number of protein modification activities are present in the protein-synthesizing complex isolated from rabbit reticulocytes. These enzymes are solubilized by sedimentation of the ribosomes through buffered sucrose containing 0.5 M KCl, and have been partially purified from the high salt wash fraction by chromatography on DEAE-cellulose and phosphocellulose. The ribosomal-associated enzymatic activities include cyclic AMP-regulated and cyclic nucloetide-independent protein kinase, phosphoprotein phosphatase, and acetyltransferase activities. These enzymatic activities have been shown to modify specific ribosomal and ribosomal-associated proteins. The cycli c AMP-regulated protein kinase phosphorylate the 40 S ribosomal subunit from rabbit reticulocytes. One of the cyclic nucleotide-independent protein kinase catalyzes the phosphorylation of two different factors involved in the initiation of hemoglobin synthesis. A single phosphoprotein phosphatase activity is shown to remove phosphate from 40 S ribosomal subunits. The major acetyltransferase activity associated with ribosomes acetylates a 60 S ribosomal protein.
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PMID:Protein modification enzymes associated with the protein-synthesizing complex from rabbit reticulocytes. Protein kinase, phosphoprotein phosphatase, and acetyltransferase. 1 14

Membrane-associated phosphoprotein phosphatase activity was demonstrated in extracts of Salmonella typhimurium and Escherichia coli. The active protein could be extracted from the membrane as a large water-soluble complex (Mr greater than 150,000). Maximal activity was observed at pH 6 to 7 in the presence of a divalent cation. The enzyme appears to be distinct from previously described phosphatases.
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PMID:Phosphoprotein phosphatase activity associated with the cytoplasmic membrane of Salmonella typhimurium and Escherichia coli. 1 33

The phosphoprotein phosphatase (phosphoprotein phosphohydrolase, EC 3.1.3.16) solubilized from human central nervous system myelin has been shown to possess a comparatively high degree of specificity towards myelin basic protein, a constituent of the membrane and most likely its natural substrate, rather than the mixed histones. The enzyme has a pH optimum of 7.5. Hydrolysis of both the substrates is stimulated by dithiothreitol and is almost completely dependent upon the presence of divalent metal ions. The maximum rate of dephosphorylation of basic protein is attained in the presence of 125 micrometer Mn2+ whereas a much higher concentration of Mg2+ (50--100 mM) is required for the optimal dephosphorylation of histones. The dephosphorylation of basic protein was also stimulated by Triton X-100 (0.15%, v/v) and was shown to result from a 3-fold increase in the V of the reaction catalyzed by the phosphatase. The apparent Km values for basic protein and histones were unaffected by the presence of Triton X-100 and were found to be approx. 1 and approx. 160 micrometer, respectively. Under optimal conditions of assay, the phosphatase cleaved approx. 32 and approx. 0.7 nmol of orthophosphate.min-1.mg-1 of protein from basic protein and histones, respectively.
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PMID:Solubilization and partial characterization of a phosphoprotein phosphatase from human myelin. 2 46

Both the microvillus and basal-lateral membrane components of intestinal epithelial cells were found to contain endogenous cyclic nucleotide-dependent protein kinases and their endogenous protein substrates. The phosphorylation of either membrane component using [gamma-32P]ATP as substrate, occurred very rapidly, reaching maximal levels at 1 min. Both cyclic AMP and cyclic GMP were shown to stimulate the phosphorylation of the microvillus and basal-lateral membranes; the approximate concentrations of cyclic AMP and cyclic GMP required for half-maximal stimulation of phosphorylation were 2 x 10(-7) M and 1.7 x 10(-8) M, respectively, for the basal-lateral membranes, and 2 x 10(-7) M and 3.2 x 10(-8) M, respectively, for the microvillus membranes. Although both membrane components were phosphorylated by an endogenous protein kinase, the microvillus membrane was consistently phosphorylated to a greater extent at maximally effective concentrations of either cyclic nucleotide. The microvillus and basal-lateral membranes were also found to contain a phosphoprotein phosphatase; however, the rate of removal of [32P]phosphate from the microvillus membrane was found to be more rapid. Neither cyclic AMP nor cyclic GMP altered the activity of the enzyme in either membrane. The present results together with earlier studies are compatible with the possibility that the regulation of water and electrolyte transport in the small intestine by cyclic AMP and cyclic GMP may be mediated through modulation of the phosphorylation of protein components of the microvillus and basal-lateral membranes.
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PMID:Cyclic nucleotide-dependent phosphorylation of rat intestinal microvillus and basal-lateral membrane proteins by an endogenous protein kinase. 2 17

Phosphoprotein phosphatase (phosphoprotein phosphohydrolase EC 3.1.3.16) activity for myelin basic protein was found to be present in the myelin fraction of rat brain. The enzyme activity was in a latent form and solubilized by 0.2% Triton X-100 treatment with about 50% increase of activity. The cytosol fraction from bovine brain also had phosphoprotein phosphatase activity for myelin basic protein, which was resolved into at least two peaks of activity on DEAE-cellulose column chromatography. Myelin basic protein was the best substrate for both the solubilized myelin fraction and the cytosol enzymes among the substrate proteins tested. The Km values of the solubilized myelin fraction were 4.2 muM for myelin basic protein, 7.4 muM for arginine-rich histone, 8.0 muM for histone mixture and 14.3 muM for protamine, respectively.
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PMID:Phosphoprotein phosphatases for myelin basic protein in myelin and cytosol fractions of brain. 4 61

We have studied the effect of protein phosphokinase (EC 2.7.1.37; ATP:protein phosphotransferase) and phosphoprotein phosphatase (EC 3.1.3.16; phosphoprotein phosphohydrolase) on reverse transcriptase (RNA-dependent DNA nucleotidyltransferase) activity of Rous sarcoma virus. Protein kinase from Rous sarcoma virus-transformed chick embryo fibroblasts was purified by DEAE-cellulose chromatography, Sephadex gel filtration, and isoelectric focusing. Purified reverse transcriptase from Rouse sarcoma virus was preincubated with protein kinase and ATP under conditions allowing incorporation of phosphate into substrate protein. After the preincubation, reverse transcriptase activity was assayed in the presence of poly(rA).oligo(dT) as template. A 2- to 5-fold increase of reverse transcriptase activity was found after the preincubation of reverse transcriptase with protein kinase and ATP. Incubation of reverse transcriptase with heat-treated, inactive protein kinase and ATP had no effect on transcriptase activity. When the transcriptase preparation was incubated with protein kinase and [gamma-32P]ATP and subsequently purified by chromatography on phosphocellulose and Sephadex gel filtration, significant amounts of 32P-labeled proteins were found in the fractions exhibiting reverse transcriptase activity, suggesting 32P incorporation into transcriptase or transcriptase-associated proteins. A 20-60% decrease of reverse transcriptase activity was observed after incubation of reverse transcriptase with phosphatase. The results suggest that phosphorylative modification of reverse transcriptase may be critical in the regulation of reverse transcriptase-catalyzed DNA synthesis.
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PMID:Protein kinase and its regulatory effect on reverse transcriptase activity of Rous sarcoma virus. 5 72

Activity of RNA-dependent DNA polymerase (RDDP) from avian myeloblastosis virus (AMV), either in purified form or in virus lysates, was increased by phosphorylation. Stability of RDDP in lysates buffered with phosphate was much greater (no loss of activity in 48 hours at 4 degrees) than that in lysates buffered with Tris-Cl (76% loss). Activity lost in the Tris-buffered extracts was completely restored by phosphorylation. The findings suggested that AMV RDDP activity is influenced by the degree of phosphorylation of the enzyme or enzyme-associated proteins and that this chemical modification is mediated by protein phosphokinase and phosphoprotein phosphatase present in crude extracts of purified AMV. Application of these results provided the basis of procedures whereby RDDP can be recovered in significantly higher yield and purity than formerly.
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PMID:Influence of phosphate on activity and stability of reverse transcriptase from avian myeloblastosis virus. 6 81


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