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)

Regulation of the avidity of LFA-1 (CD11a/CD18, alpha L beta 2) for its ligand ICAM-1 (CD54) was studied in human B cells by evaluating the effects of a phorbol ester, anti-IgM antibodies, staurosporine, and okadaic acid. We monitored changes in LFA-1 avidity by quantifying binding of cells to an immobilized rICAM-1 fusion protein. In this assay, the protein kinase C-activating phorbol ester PDB and anti-IgM antibodies, as well as the protein kinase inhibitor, staurosporine, were able to induce LFA-1-dependent binding to ICAM-1. This demonstrates that the high avidity state of LFA-1 can be induced by a protein kinase C-dependent and by a protein kinase C-independent pathway. Furthermore, treatment of the cells with the protein phosphatase inhibitor, okadaic acid, inhibited binding to ICAM-1. Treatment with staurosporine before addition of okadaic acid not only induced enhanced binding of cells to ICAM-1, but also dramatically reduced the ability of okadaic acid to inhibit binding. These results suggest a critical role for a protein phosphatase in inducing the high avidity state of LFA-1 as well as a role for a protein kinase in inducing the low avidity state of LFA-1.
...
PMID:Regulation of LFA-1 avidity in human B cells. Requirements for dephosphorylation events for high avidity ICAM-1 binding. 135 24

We have investigated the role of protracted phosphatase inhibition and the consecutive protracted protein phosphorylation on neuronal viability. We found that in primary cultures of cerebellar granule neurons, the protracted (24-h) inhibition of the serine/threonine protein phosphatases 1 and 2A (EC 3.1.3.16) by treatment of the cultures with okadaic acid (OKA; 5-20 nM) caused neurotoxicity that could be inhibited by the protein kinase inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7) or by the previous down-regulation of the neuronal protein kinase C (PKC; ATP:protein phosphotransferase; EC 2.7.1.37). PKC was down-regulated by exposure of the cultures for 24 h to 100 nM phorbol 12-myristate 13-acetate (TPA). The effect of the drugs used in the viability studies on the pattern of protein phosphorylation was measured by quantitative autoradiography. In particular, the 50- and 80-kDa protein bands showed dramatic changes in the degree of phosphorylation: increase by OKA and brief TPA treatment; decrease by H7 or 24 h of TPA treatment; and inhibition of the OKA-induced increase by H7 or 24 h of TPA treatment. The results suggest that the protracted phosphorylation, in particular that mediated by PKC, may lead to neuronal death and are in line with our previous suggestion that prolonged PKC translocation is operative in glutamate neurotoxicity.
...
PMID:Pathological phosphorylation causes neuronal death: effect of okadaic acid in primary culture of cerebellar granule cells. 140 5

Previously, the protein kinase C (PKC) inhibitor sphingosine was found to stimulate phospholipase D (PLD)-mediated hydrolysis of both phosphatidylethanolamine (PtdEtn) and phosphatidylcholine (PtdCho) in NIH 3T3 fibroblasts [Kiss & Anderson (1990) J. Biol. Chem. 265, 7345-7350]. Here we examined the possible relationship between the opposite effects of sphingosine on PKC-mediated protein phosphorylation and PLD activation. After treatments for 3-5 min, sphingosine (25 microM) and the PKC activators phorbol 12-myristate 13-acetate (PMA) (100 nM), bryostatin (100 nM) or platelet-derived growth factor (50 ng/ml) synergistically stimulated the hydrolysis of both PtdEtn and PtdCho in NIH 3T3 fibroblasts prelabelled with [14C]ethanolamine or [14C]choline. Inhibition of PMA-induced phospholipid hydrolysis could also be elicited by sphingosine, but this process required prolonged (60 min) treatments of fibroblasts with 40-60 microM-sphingosine. Similarly to sphingosine, the protein phosphatase inhibitor okadaic acid also had either potentiating or inhibitory effects on PMA-stimulated PLD activity, depending on the length of incubation time and the concentration of PMA. Consistent with the presence of an inhibitory component in the overall action of PKC, the PKC inhibitor staurosporine and down-regulation of PKC activity by prolonged (24 h) treatment with PMA similarly enhanced PLD activity. Data suggest that (a) sphingosine may enhance PMA-mediated phospholipid hydrolysis by neutralizing the action of an inhibitory PKC isoform, and that (b) the stimulatory PKC isoform is less sensitive to the inhibitory action of sphingosine.
...
PMID:Regulation of phospholipase D by sphingosine involves both protein kinase C-dependent and -independent mechanisms in NIH 3T3 fibroblasts. 147

The compound 12-O-tetradecanoylphorbol-13-acetate (TPA) is extremely toxic to the P13 subclone of the Jurkat human T-cell leukemia line. By selecting for growth in the presence of TPA, we have isolated two TPA-resistant variants of these cells, P13-50 and P13-5/A8. Studies of protein kinase C (PKC) enzyme activity, immunoblot analyses, and assays for PKC mRNAs indicate that both of these variants express lower levels of PKC than do the parental P13 cells. We suggest that this protects them from the toxic effects of TPA. The P13-5/A8 cells are of particular interest because not only are they resistant to TPA toxicity but they actually require TPA for optimal growth. These cells have a more profound decrease in PKC expression that do P13-50 cells. In addition, P13-5/A8 cells display very little, if any, surface expression of CD45, a receptor-linked tyrosine protein phosphatase, and lck, a lymphocyte-specific tyrosine kinase. On the other hand, they express a very high level of interleukin-2 receptor. A model is proposed that suggests that these cells are dependent on TPA because they have defects in both the PKC and tyrosine kinase signal transduction pathways, and that TPA compensates for these defects by providing a strong stimulus to the residual level of PKC. This variant may be useful for studying the interactions between tyrosine kinase and PKC pathways in controlling the various functions of T lymphocytes.
...
PMID:Altered expression of protein kinase C, lck, and CD45 in a 12-O-tetradecanoylphorbol-13-acetate-dependent leukemic T-cell variant that expresses a high level of interleukin-2 receptor. 153 Aug 79

A cytosolic insulin-sensitive serine kinase has been purified to apparent homogeneity in parallel from livers of control or acutely insulin-treated rats. The kinase is labile and requires rapid purification for stability. The kinase migrates as a band of apparent Mr = 90,000 on denaturing gels and elutes as a monomer on Superose 12 gel filtration. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis and renaturation, the 90-kDa band presumed to be the kinase shows kinase activity toward myelin basic protein in situ. Substrates of the kinase include Leu-Arg-Arg-Ala-Ser-Leu-Gly (Kemptide), ribosomal protein S6, S6 peptide, a proline-rich peptide substrate, microtubule-associated protein 2, and myelin basic protein. The kinase also phosphorylates histones H1 and H2B, but does not autophosphorylate to a significant stoichiometry. The activity of the kinase is inhibited by fluoride, glycerophosphate, p-nitrophenyl phosphate, p-nitrophenol, heparin, quercetin, poly-L-lysine, and potassium phosphate, but is unaffected by calcium, cAMP, spermine, protein kinase inhibitor peptide, phorbol myristate acetate, calcium plus phosphatidylserine, or vanadate. The kinase will utilize magnesium (10 mM) as well as manganese (1 mM) as a cofactor for maximal phosphotransferase activity. The kinase is not detected by immunoblotting with antibodies directed against protein kinase C or type II S6 kinase. Taken together, these properties distinguish this kinase from other insulin-sensitive kinases that have been described previously. The purified kinase from livers of insulin-treated rats shows a 5-20-fold higher specific activity compared to enzyme prepared from control rats, suggesting a covalent modification as the mechanism of activation. Incubation of purified, insulin-stimulated kinase with purified phosphatase 2A leads to deactivation of the kinase activity, and the phosphatase inhibitor nitrophenyl phosphate blocks this deactivation. The insulin-activated kinase fails to immunoblot with anti-tyrosine phosphate antibodies. Taken together, these results indicate that insulin activates this novel cytosolic protein kinase by a mechanism that causes its phosphorylation on serine or threonine residues.
...
PMID:Purification and characterization of a cytosolic insulin-stimulated serine kinase from rat liver. 153 38

The delta-subspecies of protein kinase C (delta PKC) was purified to near homogeneity from the Triton X-100 extract of the rat brain particulate fraction by successive chromatographies on S-Sepharose fast flow, phenyl 5PW, heparin 5PW, hydroxyapatite, and Mono Q columns. The purified enzyme was a doublet with molecular masses of 78 and 76 kDa on SDS/PAGE. The doublet proteins were separated partially by Mono Q column chromatography; both were recognized by the antibodies raised against synthetic oligopeptides, parts of the deduced amino acid sequence of the rat delta PKC. Protein phosphatase 2A treatment suggested that the 78-kDa protein was a phosphorylated form of the 76-kDa protein. To confirm the structural and genetic identity of the doublet proteins, delta PKC was expressed in COS 7 cells by transfecting its cDNA-constructed plasmid and was purified for comparison. This recombinant enzyme was also a doublet. The enzymes isolated from the brain and COS 7 cells showed identical reactivities with delta PKC-specific antibodies, chromatographic behaviors, and V8 protease peptide mappings. In addition, these two enzyme preparations were indistinguishable from each other in their responses to phosphatidylserine, diacylglycerol, phorbol esters, free fatty acids, Ca2+, and enzyme inhibitors. Comparison was also made between the enzymologic properties of delta PKC and alpha PKC, which were distinctly different from each other.
...
PMID:Isolation and characterization of delta-subspecies of protein kinase C from rat brain. 154 50

Casein kinase II (CKII) is one of several protein kinases that become activated before germinal-vesicle breakdown in maturing sea-star oocytes. Echinoderm CKII was purified over 11,000-fold with a recovery of approximately 10% by sequential fractionation of the oocyte cytosol on tyrosine-agarose, heparin-agarose, casein-agarose and MonoQ. The purified enzyme contained 45, 38 and 28 kDa polypeptides, which corresponded to its alpha, alpha' and beta subunits respectively. The beta-subunit was autophosphorylated on one major tryptic peptide on serine residues, whereas the alpha'-subunit incorporated phosphate into at least two tryptic peptides primarily on threonine residues. Western-blotting analysis of sea-star oocyte extracts with two different anti-peptide antibodies that recognized conserved regions of the alpha-subunit indicated that the protein levels of the alpha- and alpha'-subunits of CKII were unchanged during oocyte maturation. The purified CKII was partly inactivated (by 25%) by preincubation with protein-serine/threonine phosphatase 2A, but protein-tyrosine phosphatases had no effect. The beta-subunit of CKII was phosphorylated on a serine residue(s) up to 0.54 mol of P/mol of beta-subunit by purified protein kinase C, and this correlated with a 1.5-fold enhancement of its phosphotransferase activity with phosvitin as a substrate. CKII was not a substrate for the maturation-activated myelin basic protein kinase p44mpk from sea-star oocytes, nor for cyclic-AMP-dependent protein kinase. These studies point to possible regulation of CKII by protein phosphorylation.
...
PMID:Purification and characterization of echinoderm casein kinase II. Regulation by protein kinase C. 159 Jul 72

We have reviewed the literature, which supports an important role for dopamine withdrawal in the regulation of PRL secretion. Concentrations of dopamine in the hypophyseal portal circulation are sufficient to occupy the majority of dopamine receptors (1) and tonically suppress PRL secretion (20-26). Brief escapes from dopaminergic regulation associated with the secretion of PRL have been observed (37-41). Therefore, dopamine regulates secretion of PRL both by occupancy of, as well as dissociation from, specific D2 dopamine receptors. The rapid off rate from its receptor (2) is consistent with signals transmitted through brief decreases in dopamine concentration. The removal of dopamine for 10 min results in increases in intracellular cAMP and presumably activation of protein kinase A (39, 138) as well as activation of phospholipase C (137, 138) and protein kinase C (136). The removal of dopamine results directly in the release of PRL (37-41). Furthermore, the brief removal of dopamine results in the long-term potentiation of the PRL-releasing action of TRH (38-40). The potentiating action of dopamine withdrawal appears to be mediated by the activation of protein kinase A since pretreatment with VIP, a hormone that signals via protein kinase A, also potentiates the action of TRH (39). TRH stimulates PRL release via Ca2+/protein kinase C (177-184). The potentiating action of dopamine removal is selective for the Ca2+/protein kinase C pathway since dopamine removal does not potentiate the PRL-secreting action of VIP (38, 87, 92). The action of TRH is potentiated up to 30 min after the return of dopamine and the suppression of PRL to basal levels (38). In Fig. 10, dopamine dissociation from its receptor or VIP association to its receptor are shown separated by a broken line to indicate that by the time the potentiation of the action of TRH is tested, either dopamine is again occupying its receptor or VIP is no longer present. Therefore, the effect of protein kinase A activation is remembered by the lactotroph. We hypothesize that the responsiveness of the cell to TRH is potentiated by the phosphorylation of proteins by protein kinase A. Two potential substrates for protein kinase A are voltage-dependent Ca2+ channels and protein phosphatase inhibitors that would prolong the action of protein kinase C. When TRH occupies its receptor, intracellular Ca2+ levels are increased first from intracellular stores and subsequently by extracellular Ca2+ influx (187-189). Intracellular Ca2+ is mobilized by increased levels of IP3(128). Extracellular Ca2+ enters the lactotroph via voltage-dependent Ca2+ channels (189, 190).(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:Dissociation of dopamine from its receptor as a signal in the pleiotropic hypothalamic regulation of prolactin secretion. 161 63

Protein phosphorylation and dephosphorylation are a major mechanism for regulating cellular activity. Substantial evidence exists for ascribing a key role of protein phosphorylation and dephosphorylation in the regulation of surfactant secretion from type II pneumocytes, yet understanding of the specific molecular mechanisms is generally lacking. Herein, we report two-dimensional electrophoretic mapping of proteins phosphorylated in type II pneumocytes in primary culture, the response to protein kinase C simulation with phorbol ester, and the response to protein phosphatase inhibition with okadaic acid. Exposure of cells for 15 min to phorbol ester at a concentration (10(-4) M) which maximally stimulated both translocation of protein kinase C from cytosol to membranes and surfactant secretion increased phosphorylation (50-80% compared with control) of three specific proteins (50 kDa, pI 5.8 and 5.7; 25 kDa, pI 5.7). Exposure of cells for 2.5 h to okadaic acid (10(-6) M), a concentration that inhibited 90% of protein phosphatase activity, resulted in greatly increased phosphorylation (200-1,500% compared with control) of five specific proteins (50 kDa, pI 5.7 and 5.6; 45 kDa, pI 5.5; 40 kDa, pI 5.5; 25 kDa, pI 5.5). Combined treatment with okadaic acid and phorbol ester resulted in further increases (145-3,080% compared with control) in phosphorylation of four specific proteins (50 kDa, pI 5.6; 45 kDa, pI 5.5; 40 kDa, pI 5.5; 25 kDa, pI 5.5). We conclude that these respective proteins comprise major substrates for protein kinase C-dependent phosphorylation and for protein phosphatases in type II pneumocytes in primary culture. Furthermore, we speculate that these proteins will prove to play key roles in the regulation of type II pneumocyte function.
...
PMID:Protein phosphorylation and dephosphorylation in type II pneumocytes. 164 82

Arachidonate activation of the NADPH-oxidase in intact neutrophils and in a cell-free O2- generation system was compared to synergistic activation in response to arachidonate and agents that effect protein phosphorylation. In intact neutrophils, suboptimal doses of retinal which increase protein phosphorylation, or 4B-phorbol 12-myristate 13-acetate (PMA) an activator of protein kinase C, induced minimal O2- release, but primed neutrophils to release enhanced amounts of O2- in response to 2.5 microM arachidonate. In contrast to retinal or PMA, okadaic acid, a specific inhibitor of serine/threonine protein phosphatases, did not induce any release of O2-, but significantly increased the maximal rate and duration of O2- release in response to arachidonate. In the cell-free system, only arachidonate induced O2- generation. Consistent with previous findings, activation of the cell-free system was dependent of the presence of light membranes, cytosol, NADPH, Mg2+, and 82 microM arachidonate. Pretreatment of neutrophils with suboptimal doses of PMA or retinal had little effect on the arachidonate-stimulated release of O2- in cell-free preparations of these cells. However, cytosol (but not light membranes) from PMA or retinal-primed neutrophils was more effective in completing resting membrane NADPH-oxidase activity when compared to cytosol from resting cells. The addition of protein kinase C inhibitors staurosporine and 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine decreased the effectiveness of PMA-primed cytosol to complete the cell-free system, but had little effect on cytosol obtained from cells primed with retinal. The addition of protein phosphatase inhibitors, p-nitrophenyl phosphate or okadaic acid to neutrophil cavitates increased 3-fold the release of O2- in cell-free preparations of these cells. Okadaic acid and p-nitrophenyl phosphate also increased the effectiveness of both cytosol and light membranes to complete the cell-free system when combined with cytosol or light membranes from resting neutrophils, respectively, indicating that both fractions are affected by the inhibition of protein phosphatase activity. These data indicate that increases in protein phosphorylation alone do not lead to the activation of the NADPH-oxidase, but in addition to the requirement of an anionic amphiphile, the release of O2- from intact neutrophils or in the cell-free system is increased by stimulus activation of protein kinase C or more impressively by inhibition of protein phosphatase activity.
...
PMID:Arachidonate activation of the neutrophil NADPH-oxidase. Synergistic effects of protein phosphatase inhibitors compared with protein kinase activators. 165 30


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

---