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)

beta-Casein, and the phosphate containing peptide derived from it by tryptic digestion, have been dephosphorylated by the action of two phosphatases. Escherichia coli alkaline phosphatase (EC 3.1.3.1) has been shown to remove the phosphates from these substrates in two distinct stages. Substrate molecules retaining three of the original phosphoseryl residues accumulate during the reaction and are resistant to further dephosphorylation at low enzyme concentrations. In contrast bovine spleen phosphoprotein phosphatase (EC 3.1.3.16) achieves complete dephosphorylation of these substrates sequentially without any of the intervening species showing resistance to the action of the enzyme. The phosphopeptide has been partially dephosphorylated by the action of the two phosphatases and the resultant peptides containing three phosphoseryl residues compared in their reactivity toward the E. coli alkaline phosphatase. The results obtained are discussed in relation to the mode of action of the two enzymes.
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PMID:A study of the enzymic dephosphorylation of beta-casein and a derived phosphopeptide. 18 32

A procedure for the purification of cholesterol ester hydrolase from bovine adrenal cortical 105000 x g supernatant is described. Preincubation of a crude enzyme extract with [gamma-32P]ATP followed by purification resulted in the isolation of a phosphorylated preparation of cholesterol ester hydrolase. The phosphorylated cholesterol ester hydrolase appeared to be composed of 4 subunits, each having a molecular weight of 41000 +/- 280, only one of which may be phosphorylated. Preincubation of the crude enzyme preparation with [alpha-32P]ATP followed by purification did not produce a phosphorylated preparation of cholesterol ester hydrolase. Cyclic-AMP-dependent protein kinase, cyclic AMP, ATP and magnesium ions were required for activation of purified cholesterol ester hydrolase in vitro and the time course of activation closely paralleled the time course of phosphorylation of the enzyme. The addition of ATP, cyclic AMP and magnesium ions to the bovine adrenal cortical 105000 x g supernatant produced a 2.5-fold stimulation in cholesterol ester hydrolase activity. This stimulation was abolished if protein kinase inhibitor was added prior to the addition of ATP cyclic AMP and magensium ions. The addition of magnesium ions or calcium ions to a crude preparation of cholesterol ester hydrolase was found to inhibit activity; however the same additions made to a purified preparation of cholesterol ester hydrolase were not inhibitory. The decrease in cholesterol ester hydrolase activity on incubation with magnesium ion was accompanied by a loss of 32P radioactivity from the protein. Preincubation of a crude preparation of cholesterol ester hydrolase with alkaline phosphatase resulted in a deactivation of cholesterol ester hydrolase. It is suggested that bovine adrenal cortex cholesterol ester hydrolase is activated by a phosphorylation catalysed by a cyclic-AMP-dependent protein kinase. Deactivation of cholesterol ester hydrolase is accomplished by dephosphorylation catalysed by a phosphoprotein phosphatase, dependent on magnesium or calcium ions.
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PMID:Purification and control of bovine adrenal cortical cholesterol ester hydrolase and evidence for the activation of the enzyme by a phosphorylation. 18 99

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

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

Alkaline phosphatase from human first trimester placentas was purified, characterized, and compared with alkaline phosphatases from term placenta and liver. Three forms of first trimester placental alkaline phosphatase (I, IIa, and IIb) were isolated; their relative amounts were 35%, 39%, and 26%, respectively. Phosphatases I and IIa were found to be dimers, whereas phosphatase IIb appeared to be a tetramer consisting of two dimers of phosphatase I or IIa. Phosphatase I was indistinguishable from liver phosphatase by several criteria including apparent molecular weight (Mr = 165,000), size of the monomeric subunit (Mr = 77,000), heat liability, insensitivity to inactivation by antiserum against term placental alkaline phosphatase, and sensitivity to inactivation by antiserum against liver alkaline phosphatase. In addition, phosphatase I and liver phosphatase were equally sensitive to inhibition by amino acids, levamisole, l-p-bromotetramisole, and EDTA. Phosphatase IIa, in contrast, was indistinguishable from term placental alkaline phosphatase by the same criteria: apparent molecular weight (Mr = 115,000), size of the monomeric subunit (Mr = 63,000), heat stability, inactivation by antiserum against term placental alkaline phosphatase, and sensitivity to inhibition by various compounds. These findings clearly demonstrate the existence of two distinct placental alkaline phosphatases, one (phosphatase I) specific for the first trimester placenta and the other (phosphatase IIa) occurring in both first trimester and term placentas.
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PMID:Characterization of alkaline phosphatases from human first trimester placentas. 76 3

Treatment of mice aged 23-25 days with chorionic gonadotrophin induced large amounts of an ovarian alkaline phosphatase activity (phosphatase Ib) kinetically distinct from that of untreated ovaries (phosphatase I). The activities of alkaline phosphatase I and Ib varied with age in untreated mice. Phosphatase Ib appeared when serum luteinizing hormone concentrations increased (days 4-10 and days 35-45), and disappeared when concentrations were low (days 11-35). Injection of human chorionic gonadotrophin induced progressively larger amounts of phosphatase Ib activity between day 19 and day 29. However, gonadotrophin treatment failed to induce this activity on days 10-18 and 30-35. Nevertheless, during the latter period, human chorionic gonadotrophin induced especially large increases in uterine weight. Treatment at different ages with sheep luteinizing hormone plus human pituitary follicle-stimulating hormone induced a pattern of response identical with that induced by human chorionic gonadotrophin, although sheep luteinizing hormone alone was ineffective before 35 days. In contrast, human luteinizing hormone induced a response in the absence of exogenous follicle-stimulating hormone.
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PMID:Treatment of immature mice with gonadotrophins. The influence of mouse age on the response of ovarian alkaline phosphatase activities to gonadotrophins. 122 Jun 98

We have demonstrated that the alpha 2,3 sialyltransferase (alpha 2,3 ST) from C6 cultured glioma cells was inhibited in vivo by W-7 and related Ca2+/Calmodulin (Ca/CaM) antagonists while protein kinase C effectors had no effect. Dephosphorylation of alpha 2,3 ST by the wide specificity alkaline phosphatase led to inactivation indicating that the enzyme is phosphorylated. The serine/threonine protein phosphatase inhibitors okadaic acid and Calyculin A led also to an inhibition of alpha 2,3 ST activity. In addition, Ca/CaM antagonists and phosphatase inhibitors led both to an inhibition of a alpha 2,3 sialoglycoprotein from C6 glioma cells as demonstrated with lectin affinity blotting. A concerted regulatory mechanism with phosphorylation/dephosphorylation of alpha 2,3 ST is then postulated.
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PMID:Study of O-glycan sialylation in C6 cultured glioma cells: regulation of a beta-galactoside alpha 2,3 sialyltransferase activity by Ca2+/calmodulin antagonists and phosphatase inhibitors. 132 69

The voltage-dependent Na+ channel of the brain is a good substrate for phosphorylation by the cAMP-dependent protein kinase (protein kinase A, or PKA), but the physiological effects of PKA on Na+ channels are poorly documented. We studied modulation by PKA of voltage-dependent Na+ channels expressed in Xenopus oocytes injected with RNA coding for the alpha-subunit of the channel protein (rat brain type IIA and its variant VA200), using the two electrode voltage-clamp technique. Intracellularly injected cAMP or catalytic subunit of PKA, or extracellularly applied forskolin, inhibited the Na+ current by 20-30%. The effect of cAMP was attenuated by prior injection of PKA inhibitors. Injection of small doses of protein phosphatase 2A increased the Na+ current by 10%, whereas larger doses of protein phosphatase 1 and alkaline phosphatase were without effect. The inhibition by PKA showed little voltage dependence, being only slightly stronger at holding potentials at which the availability of the channels was reduced. The voltage dependence of activation and inactivation processes was not altered by cAMP. Similar effects were exerted by forskolin and cAMP on the Na+ channels expressed after the injection of heterologous (total) RNA from rat brain. Thus, PKA modulates the Na+ channel by a mechanism that does not involve major changes in the voltage dependency of the current and is exerted on the channel-forming alpha-subunit.
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PMID:Protein kinase A reduces voltage-dependent Na+ current in Xenopus oocytes. 138 76

Leishmania major promastigotes were analyzed for the presence of protein phosphatase activity in intact cells and membrane-enriched fractions. Parasite phosphoproteins, phosphorylated in live cells with [gamma-32P]adenosine 5'-triphosphate (ATP) and an endogenous leishmanial ectokinase, were dephosphorylated by endogenous protein phosphatase-like activity in intact cells and a membrane-rich fractions. An alkaline phosphatase-like activity was also identified using the artificial substrate, p-nitrophenyl phosphate (pNPP). This activity was localized on the extracellular membrane of intact parasites, as well as in the particulate fraction of lysed cells. The phosphatase activity measure using pNPP had inhibition properties and a pH profile between protein phosphatase and general alkaline phosphatases. This study supports the observation that there is extracellular protein phosphorylation/dephosphorylation in L. major which may play a significant role in host cell-parasite recognition and infection.
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PMID:Extracellular dephosphorylation in the parasite, Leishmania major. 166 66

A combination of planar bilayer and patch-clamp techniques was used to determine whether apical membrane Cl- channels of shark (Squalus acanthias) rectal gland (SRG) were regulated by a phosphorylating and dephosphorylating cycle. In channel reconstitution studies, apical membrane vesicles of SRG were purified, incubated in ATP-Mg2+ and the presence or absence (control) of catalytic subunit of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (cAMP-PK) and incorporated into planar lipid bilayers. In the presence of cAMP-PK, two distinct Cl- channels were found when imposing either 450/50 or 300/50 mM KCl (cis/trans) gradients. The most frequently observed channels (G beta 1) were open greater than 80% at all potentials between -60 and +20 mV (trans ground) and were inactivated by alkaline phosphatase added to the cis chamber. The single-channel conductance of G beta 1 was 42 pS between -60 and +20 mV with a 300/50 mM KCl gradient. The second channel (G beta 2) was always observed in pairs of 62-pS subchannels and was not affected by alkaline phosphatase, but the open probability increased with depolarizing potentials. G beta 2 was observed once, but G beta 1 was never observed in the absence of cAMP-PK. In parallel patch-clamp studies of the apical membrane of cultured SRG, a 50-pS channel similar to G beta 1 was noted after incubating cells with either forskolin, an activator of adenylate cyclase, or okadaic acid, an inhibitor of protein phosphatases 1 and 2A. It is concluded that G beta 1 of SRG can be studied in both patch-clamp and bilayer preparations and that G beta 1 is regulated by reversible phosphorylation by cAMP-PK and dephosphorylation by a protein phosphatase.
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PMID:Regulation of epithelial chloride channels by protein phosphatase. 171 76


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