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

---

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

The photoaffinity label 8-azido[32P]adenosine 3':5'-monophosphate (8-azido-cyclic [32P]AMP) was used to analyze both the cAMP-binding component of the purified cAMP-dependent protein kinase, and the cAMP-binding proteins present in crude tissue extracts of bovine cardiac muscle. 8-Azido-cyclic [32P]AMP reacted specifically and in stoichiometric amounts with the cAMP-binding proteins of bovine cardiac muscle. Upon phosphorylation, the purified cAMP-binding protein from bovine cardiac muscle changed its electrophoretic mobility on sodium dodecyl sulfate-polyacrylamide gels from an apparent molecular weight of 54,000 to an apparent molecular weight of 56,000. In tissue extracts of bovine cardiac muscle, most of the 8-azido-cyclic [32P]AMP was incorporated into a protein band with an apparent molecular weight of 56,000 which shifted to 54,000 upon treatment with a phosphoprotein phosphatase. Thus a substantial amount of the cAMP-binding protein appeared to be in the phosphorylated form. Autoradiograms following sodium dodecyl sulfate-polyacrylamide gel electrophoresis of both the pure and impure cAMP-binding proteins labeled with 8-azido-cyclic [32P]AMP revealed another binding component with a molecular weight of 52,000 which incorporated 32P from [gamma-32P]ATP without changing its electrophoretic mobility. Limited proteolysis of the 56,000- and 52,000-dalton proteins labeled with 32P from either [gamma-32P]ATP.Mg2+ or 8-azido-cyclic [32P]AMP showed patterns indicating homology. On the other hand, peptide maps of the major 8-azido-cyclic [32P]AMP-labeled proteins from tissue extracts of bovine cardiac muscle (Mr = 56,000) and rabbit skeletal muscle (Mr = 48,000) displayed completely different patterns as expected for the cAMP-binding components of types II and I protein kinases. Both phospho- and dephospho-cAMP-binding components from the purified bovine cardiac muscle protein kinase were also resolved by isoelectric focusing on polyacrylamide slab gels containing 8 M urea. The phosphorylated forms labeled with 32P from either [gamma-32P]ATP or 8-azido-cyclic [32P]AMP migrated as a doublet with a pI of 5.35. The 8-azido-cyclic [32P]AMP-labeled dephosphorylated form also migrated as a doublet with a pI of 5.40. The phosphorylated and dephosphorylated cAMP-binding proteins migrated with molecular weights of 56,000 and 54,000, respectively, following a second dimension electrophoresis in sodium dodecyl sulfate. The lower molecular weight cAMP-binding component (Mr = 52,000) was also apparent in these gels. Similar experiments with the cAMP-binding proteins present in tissue extracts of bovine cardiac muscle indicate that they are predominantly in the phosphorylated form.
...
PMID:Resolution of the phosphorylated and dephosphorylated cAMP-binding proteins of bovine cardiac muscle by affinity labeling and two-dimensional electrophoresis. 21 41

The regulation of protein synthesis at the level of the ribosome was investigated using the model system of ethionine-induced inhibition of protein synthesis. The phosphorylation of ribosomal protein S6 was examined in vivo during ethionine intoxication and during the adenine-induced reversal of ethionine intoxication. The extent of phosphorylation of S6 correlated well with protein synthetic activity observed after ethionine, and ethionine followed by adenine treatments. No clear correlation was observed in the ethionine system between cyclic adenosine 3':5'-monophosphate concentration or the activity of ribosomal protein kinase and the phosphorylation of ribosomal protein S6. A role for a cyclic adenosine 3':5'-monophosphate-dependent ribosomal phosphoprotein phosphatase is postulated.
...
PMID:Protein kinase activity and ribosome phosphorylation in ethionine-treated rats. 21 48

LH-induced desensitization of the adenylyl cyclase system in a cell-free membrane preparation from preovulatory porcine follicles exhibits a critical dependence upon Mg and ATP (1). The membrane-rich preparation was found to contain endogenous cAMP-dependent and cAMP-independent protein kinases as well as phosphorprotein phosphatases. Endogenous phosphatase activity was enchanced by by Mn2+ and dithiothreitol. The addition of either Mn2+ or dithiothreitol to the porcine follicular membrane preparation incubated under desensitizing conditions promoted a specific concentration-dependent reversal of the LH-induced desensitization of the adenylyl cyclase system. The addition of exogenous phosphoprotein phosphatase, partially purified from procine follicular cytosol, also reversed LH-induced desensitization in a concentration-dependent manner. Boiling of the phophatase preparation prevented reversal of desensitization. The addition of either exogenous beef heart cAMP-dependent protein kinase or heat-stable protein kinase inhibitor did not modify LH-induced desensitization of the follicular adenylyl cyclase system. These results provide indirect evidence that while LH-induced desensitization is not mediated by a cAMP-dependent protein kinase, reversal of desensitization can be promoted by activation of endogenous phosphatase and the addition of a homologous phosphatase preparation.
...
PMID:Resensitization of the desensitized follicular adenylyl cyclase system to luteinizing hormone. 22 Nov 92

Alterations in content of glycogen as well as in activity of phosphorylase and phosphoprotein phosphatase were studied in various rat tissues after intravenous administration of a new hypothalamic hexapeptide Tyr-Gly-Leu-Pro-Gly-NH2. An increase in phosphoprotein phosphatase activity was observed in heart muscle, which correlated with transformation of phosphorylase A to the B form and with accumulation of glycogen. The opposite effect was found in liver tissue and sceletal muscle.
...
PMID:[Molecular mechanisms of hypothalamic hexapeptide regulation of the links in glycogen metabolism]. 22 71

Studies on the gonadotrophin-responsive adenylyl cyclase (AC) system of rabbit and porcine ovarian follicles reveal that hCG or LH-induced desensitization of the AC system can be divided into two phases: an initial, LH-specific phase and a second phase which is not specific for LH. The first phase occurs within the first hour after LH-hCG-receptor interaction, is agonist specific, and is not mediated by protein synthetic events or by cAMP. In view of our previous demonstration of the critical dependence of the LH-induced desensitizing process in cell-free membrane preparations of porcine follicles upon Mg2+ and ATP, we investigated the role of a phosphorylation reaction in the first phase of the AC desensitizing process. Porcine follicular membranes rich in LH-sensitive AC activity were found to contain the molecular requirements necessary for a phosphorylation reaction: namely, cAMP-dependent and cAMP-independent protein kinases as well as phosphoprotein phosphatases. The following lines of indirect evidence indicated that reversal or resensitization of the desenzitized AC system to LH was mediated by a dephosphorylation reaction. Activators of endogenous phosphoprotein phosphatases--Mn2+ and dithiothreitol--promoted a specific resensitization of the follicular AC system to LH. Likewise, a partially purified phosphoprotein phosphatase also resensitized the desensitized, LH unresponsive AC to LH, and boiling of the phosphatase prevented its effect. LH-induced desensitization of the AC system, on the other hand, did not appear to be mediated by a cAMP-dependent protein kinase, as evidenced both by the inability of beef heart protein to promote desensitization of AC and by the inability of an inhibitor of cAMP-dependent protein kinase to prevent LH-induced densensitization. The second phase of desensitization, which occurs after the first hour following hCG-LH-receptor interaction, is characterized by a loss of responsiveness to FSH as well as to LH and can be promoted by dibutryl cAMP (in the absence of LH). These results provide new evidence on the characteristics and molecular mechanism of LH-induced densensitization of the follicular AC system. These results indicate that the level of phosphorylation of membrane-associated components may, in part, regulate the activity of the AC system during this first phase of homologous desensitization.
...
PMID:LH-induced desensitization of the adenylyl cyclase system in ovarian follicles. 22 90

Using 32P-labeled phosphocasein or phosphohistones as exogenous substrates it was possible to detect a phosphoprotein phosphatase activity on the outer surface of intact normal and transformed 3T3 fibroblasts. Incubation of monolayers of intact cells in buffered salt solution with the radioactively labeled substrate resulted in the release of alkali-labile 32P counts into the surrounding medium. The reaction was: (a) linear with time (at least up to 20 min); (b) proportional to the cell density; (c) dependent on the temperature and pH of the incubation medium; (d) stimulated by K+; and (e) inhibited by sodium fluoride, inorganic pyrophosphate, zinc chloride and relatively impermeant sulfhydryl reagents. Less than 2% of the externally located phosphoprotein phosphatase activity was detectable in pooled cell-free washings of the intact cell monolayer. Phosphocasein did not cause any detectable leakage of intracellular lactate dehydrogenase or soluble phosphoprotein phosphatase activity into the external medium; incubation of the cells with phosphohistones, on the other hand, resulted in appreciable leakage of both these cytoplasmic activities. Neoplastic transformation was associated with a nearly two-fold decrease in the activity of the surface phosphoprotein phosphatase. Addition of serum to either non-transformed 3T3 or spontaneously transformed 3T6 cells resulted in a rapid and remarkeable drop in the cell surface dephosphorylating activity. Acrylamide gel electrophoresis of the dephosphorylated casein or histone substrate revealed no proteolytic degradation or change in electrophoretic mobility. The intact cells showed no damage upon microscopic examination as a result of exposure to phosphocasein or phosphohistones.
...
PMID:Phosphoprotein phosphatase activity at the outer surface of intact normal and transformed 3T3 fibroblasts. 22 67

Interferon-treated L cells are characterized by an increased protein kinase activity that can selectively phosphorylate the small subunit of eukaryotic initiation factor 2. This protein kinase, PK-i, has been extensively purified and shown to be a potent inhibitor of mRNA translation. The purified PK-i contains the endogenously phosphorylated 67,000 Mr protein characteristic of interferon-treated cell extracts. PK-i can also phosphorylate arginine-rich histones. Purified PK-i can be activated by preincubation with ATP (but not adenylyl imidodiphosphate) and low concentrations of double-stranded RNA. The activation results in an increase in the first rate of eIF-2 phosphorylation. Activated PK-i becomes resistant to high concentrations of double-stranded RNA and more thermostable. A stimulator of PK-i activity, factor A, was isolated, as well as a specific phosphoprotein phosphatase that dephosphorylates the 67,000 Mr protein and eIF-2. These two factors, which are present in untreated L cells, may regulate the translation inhibitory activity of the interferon-induced and double-stranded RNA-activated protein kinase PK-i.
...
PMID:The interferon-induced protein kinase PK-i from mouse L cells. 22 29

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.
...
PMID:The control of phosphoprotein phosphatase by the second-site phosphorylation of a substrate. Studies with H2B histone as model substrate. 22 81

Deproteinized skeletal muscle extracts free of major nucleotides from control and insulin-treated rats were fractionated and assayed for inhibition of protein phosphorylation by cyclic adenosine monophosphate (AMP)-dependent and -independent protein kinases. A differential effect of insulin on a particular fraction was observed on cyclic AMP-dependent protein kinase but not on cyclic AMP-independent protein kinases. This fraction that inhibited cyclic AMP-dependent protein kinase also stimulated glycogen synthase phosphoprotein phosphatase. It is proposed that this fraction may contain a mediator substance generateed in the presence of insulin.
...
PMID:Generation by insulin of a chemical mediator that controls protein phosphorylation and dephosphorylation. 22 95

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.
...
PMID:Cardiac myofibrillar phosphorylation and adenosine triphosphatase activity. 22 75


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---