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 effect of regucalcin, a Ca2+-binding protein, on Ca2+/calmodulin-dependent phosphatase activity in rat renal cortex cytosol was investigated. The addition of Ca2+/calmodulin in the enzyme reaction mixture caused a significant increase in the dephosphorylation of p-nitrophenylphosphate and phosphotyrosine used as the substrate for phosphatase in rat renal cortex cytosol. The presence of regucalcin (10(-6) M) in the enzyme reaction mixture caused a complete inhibition of Ca2+/calmodulin-dependent phosphatase activity in renal cortex cytosol. A half maximum effect of regucalcin inhibition was seen at 10(-8) M concentration. Moreover, phosphatase activity of purified calcineurin was significantly enhanced by the addition of Ca2+/calmodulin. This enhancement was completely inhibited by the presence of regucalcin (10(-7) M). The inhibitory effect of regucalcin was not weakened by increasing concentrations of CaCl2 (10(-6) to 10(-4) M). The present results suggest that regucalcin can inhibit Ca2+/calmodulin-dependent phosphatase activity in rat renal cortex.
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PMID:Inhibitory effect of regucalcin on Ca2+/calmodulin-dependent phosphatase activity in rat renal cortex cytosol. 963 96

The effect of calcium-binding protein regucalcin on phosphatase activity in the brain cytosol of rats with different ages was investigated. The presence of regucalcin (10(-8) and 10(-7) M) in the enzyme reaction mixture caused a significant increase of neutral p-nitrophenylphosphatase activity in the brain cytosol obtained from 5- and 50-week-old rats. This increase was seen in the absence or presence of calmodulin (2 microg/mL) and calcium chloride (100 microM). Brain cytosolic phosphatase activity was not significantly altered by S-100A (10(-6) M) or calbindin (10(-7) M), which is a calcium-binding protein. Regucalcin-increased phosphatase activity was clearly decreased by N-ethylmaleimide, a modifying reagent of thiol(SH)-group, suggesting that regucalcin acts on the SH-group of the enzyme. Moreover, the presence of anti-regucalcin monoclonal antibody (50-200 ng/mL) in the reaction mixture caused a significant decrease of brain cytosolic phosphatase activity, suggesting that the endogenous regucalcin has a stimulatory effect on the enzyme activity. These results suggest that regucalcin plays a role in the regulation of protein phosphatase in rat brain cytosol.
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PMID:Stimulatory effect of calcium-binding protein regucalcin on phosphatase activity in the brain cytosol of rats with different ages. 967 Dec 64

The regulatory effect of regucalcin on Ca2+/calmodulin-dependent phosphatase activity and the binding of regucalcin to calmodulin was investigated. Phosphatase activity toward phosphotyrosine, phosphoserine, and phosphothreonine in rat liver cytosol was significantly increased by the addition of Ca2+ (100 microM) and calmodulin (0.30 microM). These increases were clearly inhibited by the addition of regucalcin (0.50-1.0 microM) into the enzyme reaction mixture. The cytosolic phosphoamino acid phosphatase activity was significantly elevated by the presence of anti-regucalcin monoclonal antibody (0.2 microg/ml), suggesting that endogenous regucalcin in the cytosol has an inhibitory effect on the enzyme activity. This elevation was prevented by the addition of regucalcin (0.50 microM). Purified calcineurin phosphatase activity was significantly increased by the addition of calmodulin (0.12 microM) in the presence of Ca2+ (1 and 10 microM). This increase was completely inhibited by the presence of regucalcin (0.12 microM). The inhibitory effect of regucalcin was reversed by the addition of calmodulin with the higher concentration (0.36 microM). Regucalcin has been demonstrated to bind on calmodulin-agarose beads by analysis with sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The present study demonstrates that regucalcin inhibits Ca2+/calmodulin-dependent protein phosphatase activity in rat liver cytosol, and that regucalcin can bind to calmodulin.
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PMID:Inhibition of Ca2+/calmodulin-dependent phosphatase activity by regucalcin in rat liver cytosol: involvement of calmodulin binding. 973 62

The role of endogenous regucalcin (RC) in the regulation of neutral phosphatase activity in regenerating rat liver was investigated. The liver weight reduced by a partial hepatectomy (about 70%) was completely restored at 72 h after surgery. Phosphotyrosine, phosphoserine, and phosphothreonine were used as the substrate for the assay of phosphatase activity. Phosphatase activity toward phosphotyrosine in the hepatic cytosol and nuclei was significantly increased at 24-72 h after hepatectomy. Such an increase was not seen in the case of phosphoserine and phosphothreonine. However, the presence of anti-RC monoclonal antibody (200 ng/ml) in the enzyme reaction mixture caused a remarkable elevation of phosphatase activity toward three phosphoaminoacids in the hepatic cytosol at 24 and 48 h after hepatectomy. In the liver nuclei after sham operation or hepatectomy, phosphatase activity toward three phosphoaminoacids was significantly raised by the addition of anti-RC antibody (150 ng/ml). The nuclear phosphatase activity toward phosphothreonine in regenerating liver was significantly enhanced in the presence of anti-RC antibody (100 and 150 ng/ml). The effect of anti-RC antibody to increase phosphatase activity toward three phosphoaminoacids in the cytosol and nuclei of regenerating liver was completely blocked by the addition of exogenous RC (1.0 microM). The present study demonstrates that protein phosphatase activity in the cytoplasm and nuclei is enhanced in regenerating rat liver. This enhancement may be suppressed by endogenous RC.
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PMID:Enhancement of neutral phosphatase activity in the cytosol and nuclei of regenerating rat liver: role of endogenous regucalcin. 1032 33

The effect of Ca2+-binding protein regucalcin on neutral phosphatase activity in rat brain cytosol was investigated. Phosphatase activity was assayed in a reaction mixture containing the cytosolic protein in the presence of phosphotyrosine, phosphoserine, and phosphothreonine. The presence of calcium chloride (10(-5) and 10(-4) M) in the enzyme reaction mixture caused a significant increase in phosphatase activity toward three phosphoaminoacids. The enzyme activity toward phosphoserine and phosphothreonine was significantly enhanced by the addition of calmodulin (1 or 5 microg/ml) in the presence of calcium (10(-5) M). Such an effect was not seen in the presence of phosphotyrosine. Trifluoperazine (2x10(-5) M), an antagonist of calmodulin, completely inhibited calcium (10(-5) M)-increased phosphatase activity toward phosphoserine and phosphothreonine, whereas it had no effect on the enzyme activity toward phosphotyrosine. Regucalcin (10(-9) M) significantly inhibited phosphatase activity toward three phosphoaminoacids without or with Ca2+ addition. The inhibitory effect of regucalcin (10(-10) and 10(-9) M) was also seen in the presence of Ca2+ (10(-5) M) and calmodulin (5 microg/ml). The presence of anti-regucalcin monoclonal antibody (20 or 50 ng/ml) in the enzyme reaction mixture caused a significant elevation of phosphatase activity toward three phosphoaminoacids; this effect was completely abolished by addition of regucalcin (10(-9) M). The present study suggests that the endogenous regucalcin has an inhibitory effect on Ca2+/calmodulin-dependent protein phosphatase activity in rat brain cytosol.
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PMID:Inhibitory effect of regucalcin on Ca2+/calmodulin-dependent protein phosphatase activity in rat brain cytosol. 1034 Dec 92

The effect of anti-regucalcin monoclonal antibody on neutral phoshatase activity in rat liver cytosol was investigated. Phosphotyrosine, phosphoserine, and phosphothreonine were used as the substrate toward phosphatase assay. Liver cytosolic phosphatase activity with three phosphoaminoacids was significantly increased in the presence of anti-regucalcin antibody (100 and 200 ng/ml) in the enzyme reaction mixture with calcium chloride (0.1 mM) or EGTA (1.0 mM). The effect of anti-regucalcin antibody was completely abolished in the presence of exogenous regucalcin (1.0 microM), indicating the involvement of endogenous regucalcin. The anti-regucalcin anti body- increased phosphatase activity was not significantly altered in the presence of trifluoperazine (20 microM), an antagonist of calmodulin, or akadaic acid ( 10 microM), an inhibitor of protein phosphatase, although these inhibitors caused a slight decrease in liver cytosolic phosphatase activity. The effect of endogenous regucalcin might be not related to calmodulin, and it was insensitive to okadaic acid. The present findings suggest that endogenous regucalcin is involved in the regulation of protein phasphatase in rat liver cytoplasm.
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PMID:Effect of anti-regucalcin antibody on neutral phosphatase activity in rat liver cytosol: involvement of endogenous regucalcin. 1048 20

The regulatory role of regucalcin on protein phosphatase activity in isolated rat liver nuclei was investigated. Phosphatase activity toward phosphotyrosine and phosphoserine was significantly increased by the addition of CaCl(2) (10(-5) and 10(-4) M) in the enzyme reaction mixture. Trifluoperazine (25 and 50 microM), an antagonist of calmodulin, significantly inhibited protein phosphatase activity toward phosphoserine, while it had no effect on the enzyme activity toward phosphotysine and phosphothreonine. Cyclosporin A (10(-6)-10(-4) M), an inhibitor of Ca(2+)/calmodulin-dependent protein phosphatase activity toward phosphoserine, but not phosphotyrosine and phosphoserine. Thus, Ca(2+)/calmodulin-dependent phosphatases were present in liver nuclei. Regucalcin (0.25 and 0.5 microM) had an inhibitory effect on liver nuclear phosphatase activity toward phosphotyrosine, phosphoserine, and phosphothreonine. The presence of anti-regucalcin monoclonal antibody (25 and 50 ng/ml) in the enzyme reaction mixture caused a significant elevation of nuclear phosphatase activity toward three phosphoaminoacids. An analysis with sodium sulfate-polyacrylamide gel electrophoresis suggested a possibility of localization of regucalcin in liver nuclei. Moreover, regucalcin was determined in liver nuclei using enzyme-linked immunoadsorbent assay. The present study demonstrates that the endogenous regucalcin inhibits phosphatase activity in the liver nuclei.
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PMID:Regulation of protein phosphatase activity by regucalcin localization in rat liver nuclei. 1053 67

Regucalcin was discovered in 1978 as a calcium-binding protein that does not contain EF-hand motif of Ca(2+)-binding domain [M. Yamaguchi and T. Yamamoto, Chem. Pharm. Bull. 26 1915-1918 (1978)]. In recent years, regucalcin has been demonstrated to play an important role as a regulatory protein in Ca2+ signaling in rat liver and kidney cells. The organization of the rat regucalcin gene consists of seven exons and six introns. The mRNA is mainly present in liver and kidney with a size of 1.8 kb. Hepatic regucalcin mRNA expression has been shown to be stimulated by various factors including calcium, calcitonin, insulin, and estrogen in rats. The mRNA is also expressed in hepatoma cells (Morris hepatoma, HepG2, and rat hepatoma H4-II-E cells). Regucalcin plays a role in the maintenance of intracellular Ca2+ homeostasis due to activating Ca2+ pump enzymes in the plasma membrane (basolateral membrane) and microsomes of liver and renal cortex cells. Moreover, regucalcin has an inhibitory effect on the activation of Ca2+/calmodulin-dependent enzymes and protein kinase C. Also, regucalcin has been demonstrated to regulate nuclear function in liver cells; it can inhibit Ca(2+)-activated DNA fragmentation, DNA and RNA synthesis, protein kinase and protein phosphatase activities in the nuclei. Such an effect is also seen in the nuclei of regenerating rat liver. Regucalcin may play a physiological role in the control for overexpression of proliferative cells. Regucalcin has been proposed to be an important regulatory protein in Ca2+ signaling system, and it plays a multifunctional role in liver and kidney cells.
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PMID:Role of regucalcin in calcium signaling. 1080 75

The expression of Ca(2+)-binding protein regucalcin and its role in the regulation of protein phosphatase activity in rat brain neuronal cells obtained with primary culture was investigated. The expression of regucalcin mRNA was demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) analysis in brain neuronal cells using rat regucalcin-specific primers. Moreover, regucalcin protein in brain neuronal cells was detected by Western blot analysis using a polyclonal rabbit anti-regucalcin antibody. The presence of anti-regucalcin monoclonal antibody (20 or 50 ng/ml) in the enzyme reaction mixture caused a significant increase in protein phosphatase activity toward phosphotyrosine, phosphoserine and phosphothreonine in the reaction mixture containing the cytosol of neuronal cell homogenates. This increase was completely prevented by the addition of regucalcin (10(-8) M). Protein phosphatase activity toward three phosphoaminoacids was significantly elevated by the addition of Ca(2+) (100 microM) and calmodulin (5 microg/ml). This elevation was completely blocked by the addition of regucalcin (10(-8) M). The present study demonstrates that regucalcin is expressed in rat brain neuronal cells, and that it has an inhibitory effect on protein phosphatase activity in the cells.
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PMID:Expression of Ca(2+)-binding protein regucalcin in rat brain neurons: inhibitory effect on protein phosphatase activity. 1092 12

The role of endogenous regucalcin in the regulation of protein tyrosine phosphatase activity in the proliferation of the cloned rat H4-II-E hepatoma cells was investigated. Cells were cultured for 6 to 96 h in a medium containing 1.0 or 10% fetal bovine serum (FBS). Cell numbers were significantly raised by culture with 10% FBS in comparison with that of 1.0% FBS. Protein tyrosine phosphatase activity in the cells was significantly elevated by culture with 10% FBS for 24 to 96 h as compared with that of 1% FBS. Such an increase was not seen in protein phosphatase activity toward phosphoserine or phosphothreonine. The presence of anti-regucalcin monoclonal antibody (50 or 100 ng/ml) in the enzyme reaction mixture caused a remarkable elevation of protein tyrosine phosphatase activity in the cells obtained by culture with 1.0 or 10% FBS. This elevation was completely prevented by the addition of regucalcin (10-6 M). The effect of antibody in elevating protein tyrosine phosphatase activity in the cells was significantly inhibited by the addition of okadaic acid (10-6 M) or vanadate (10(-6) M), an inhibitor of protein phosphatase, in the reaction mixture. The present study suggests that protein tyrosine phosphatase activity in the cloned rat hepatoma cells is increased in serum-stimulated cell proliferation, and that endogenous regucalcin has a suppressive role in the enhancement of the enzyme activity in proliferative cells.
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PMID:Enhancement of protein tyrosine phosphatase activity in the proliferation of cloned rat hepatoma H4-II-E cells: suppressive role of endogenous regucalcin. 1093 98


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