Oxonium ion intermediates in the rearrangement of thebaine

Channon, R. T.; Kirby, G. W.; Massey, Sylvia

doi:10.1039/j39690001215

Cited by 76 publications

(106 citation statements)

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“…Calcium ions at an elevated level induced the translocation of the enzyme from the cytosol to the membrane (Yoshihara and Watanabe, 1990; Channon and Leslie, 1990;Krause et al, 1991 ;Clark et al, 1991 ;Ghomashchi e t al., 1992). Addition of 2 m M EGTA to a mixture of dialkylPtdCho and lysoPtdCho suppressed the lysophospholipase activity partially.…”

Section: Discussionmentioning

confidence: 99%

“…First, cPLA, hydrolyzes arachidonoyl residues preferentially (Kim et al, 1988;Clark et al, 1991 ;Sharp et al, 1991). Second, its catalytic activity (Leslie et al, 1988;Kim et al, 1991;Wijkander and Sundler, 1991;Takayama et al, 1991) and subcellular localization (Yoshihara and Watanabe, 1990;Channon and Leslie, 1990;Krause et al, 1991 ;Clark et al, 1991) are regulated by physiological concentrations of calcium. Third, cultured cells in which the gene encoding human cPLA, is overexpressed generate more arachidonate in response to extracellular stimuli (Clark et al, 1991;Lin et al, 1992a).…”

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confidence: 99%

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Characteristics of lysophospholipase activity expressed by cytosolic phospholipase A₂

Fujimori

Kudo

Fujita

et al. 1993

European Journal of Biochemistry

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Evidence has accumulated to suggest that a wide variety of mammalian cells and tissues express a cytosolic phospholipase A, with arachidonoyl preference (cPLA,). Purified rabbit platelet-derived cPLA,, as well as the human recombinant enzyme originally identified in the monocytic leukemic cell line U937, exhibit significant lysophospholipase activity. Several series of experiments indicated that a single protein mediated both activities. Treatment of the purified enzyme with p-bromophenacylbromide or an anti-(rabbit platelet cPLA,) monoclonal antibody, RHY-5, suppressed the activity of phospholipase A, without any appreciable effect on lysophospholipase activity, suggesting that the domain(s) required for phospholipase A, activity may be located separately from that for lysophospholipase activity. Lysophospholipase activity was appreciably detected above the critical micellar concentration of the substrate. Ly sophosphatidylcholine was also hydrolyzed efficiently when it was incorporated into liposomes made of dialkylphosphatidylcholine. The hydrolysis of lysophospholipid was dependent on the fatty acid bound at the sn, position; the relative rates of hydrolysis of 1 -oleoyllysophosphatidylcholine, 1-palmitoyllysophosphatidylcholine, and l-stearoyllysophosphatidylcholine were 23, 8, and 1, respectively. A similar order of reactivity was observed with lysophospholipid incorporated into dialkylphosphatidylcholine liposomes. cPLAz may function not only as an arachidonate liberation enzyme but also as an enzyme responsible for degradation of certain molecular species of lysophospholipids formed in membranes.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Characteristics of lysophospholipase activity expressed by cytosolic phospholipase A₂

Fujimori

Kudo

Fujita

et al. 1993

European Journal of Biochemistry

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“…Calcium is not required for catalytic activity of cPLA 2 but is required for binding of the cPLA 2 to phospholipid vesicles (6 -8). Calcium-dependent membrane binding of cPLA 2 occurs at calcium concentrations of 300 nM or greater and is mediated by a calcium-dependent lipid binding domain present at the amino terminus of cPLA 2 (6,9,10). Stimulation of mast cells by calcium ionophore or by IgE/ antigen has recently been shown to induce translocation of the cPLA 2 from the cytosol to the nuclear membrane (11).…”

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confidence: 99%

Identification of Phosphorylation Sites of Human 85-kDa Cytosolic Phospholipase A2 Expressed in Insect Cells and Present in Human Monocytes

Carvalho

McCormack

Olson

et al. 1996

Journal of Biological Chemistry

145

159

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The phosphorylation sites on the human, 85-kDa cytosolic phospholipase A 2 (cPLA 2 ) were identified using recombinant cPLA 2 expressed in Spodoptera frugiperda (Sf9) cells. Analysis by high performance liquid chromatography of tryptic digests of 32 P-labeled recombinant cPLA 2 showed four major peaks of radiolabeled phosphopeptides. The phosphorylated residues were identified as Ser-437, Ser-454, Ser-505, and Ser-727 using mass spectrometry and automated Edman sequencing. Sf9 cells infected with recombinant virus expressing cPLA 2 exhibited a time-dependent release of arachidonic acid in response to the calcium ionophore A23187 or the protein phosphatase inhibitor okadaic acid, which was not observed in Sf9 cells infected with wild-type virus. Stimulation of Sf9 cells with A23187 and okadaic acid also increased the level of phosphorylation of cPLA 2 . Okadaic acid, but not A23187, induced a gel shift of cPLA 2 and increased the level of phosphorylation of Ser-727 by 4.5-fold, whereas the level of phosphorylation of the other sites increased by 60% or less in response to both agonists. To determine whether the same sites on cPLA 2 were phosphorylated in mammalian cells, human monocytes were studied. Okadaic acid stimulation of monocytes induced a gel shift of cPLA 2 , increased the release of arachidonic acid, and increased the level of phosphorylation of cPLA 2 on serine residues. Comparison of two-dimensional peptide maps of tryptic digests of 32 Plabeled recombinant cPLA 2 and human monocyte cPLA 2 demonstrated that the same peptides on cPLA 2 were phosphorylated in mammalian cells as in insect cells. These results show that the Sf9-baculovirus expression system is useful for investigation of the phosphorylation sites on cPLA 2 . The results also suggest that phosphorylation of the cPLA 2 by protein kinases other than mitogen-activated protein kinase may be important for the regulation of arachidonic acid release.

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“…This suggests that the elevated [Ca2+]i acts on arachidonic acid release via Ca2+/ calmodulin as previously shown in human platelet [27] and medullary [28] subcellular preparations. Recently, Ca2+ induction of phospholipase A2 has been suggested to be due to Ca2+-induced translocation of the enzyme from cytosol to membranes where the enzyme is facilitated to react with its substrates [29][30][31]. This idea was supported by the finding of a Ca2+_ dependent translocation domain with homology to protein kinase C and GTPase-activating protein, in a cytosolic phospholipase A2 of monocytic leukaemic U937 cells [31].…”

Section: Role Of [Ca2+] Increase and Protein Kinase C Activation In mentioning

confidence: 99%

Permissive stimulation of Ca(2+)-induced phospholipase A2 by an adenosine receptor agonist in a pertussis toxin-sensitive manner in FRTL-5 thyroid cells: a new ‘cross-talk’ mechanism in Ca2+ signalling.

Shimegi

Okajima

Kondo

1994

Biochemical Journal

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We have described the pertussis toxin (PTX)-sensitive potentiation of P2-purinergic agonist-induced phospholipase C activation, Ca2+ mobilization and arachidonic acid release by an adenosine receptor agonist, N6-(L-2-phenylisopropyl)adenosine (PIA), which alone cannot influence any of these cellular activities [Okajima, Sato, Nazarea, Sho and Kondo (1989) J. Biol. Chem. 264, 13029-13037]. In the present study we have found that arachidonic acid release was associated with lysophosphatidylcholine production, and conclude that arachidonic acid is produced by phospholipase A2 in FRTL-5 thyroid cells. This led us to assume that PIA augments P2-purinergic arachidonic acid release by increasing [Ca2+]i which, in turn, activates Ca(2+)-sensitive phospholipase A2. The arachidonic acid-releasing response to PIA was, however, always considerably higher (3.1-fold increase) than the Ca2+ response (1.3-fold increase) to the adenosine derivative. In addition, arachidonic acid release induced by the [Ca2+]i increase caused by thapsigargin, an endoplasmic-reticulum Ca(2+)-ATPase inhibitor, or calcium ionophores was also potentiated by PIA without any effect on [Ca2+]i and phospholipase C activity. This action of PIA was also PTX-sensitive, but not affected by the forskolin- or cholera toxin-induced increase in the cellular cyclic AMP (cAMP), suggesting that a PTX-sensitive G-protein(s) and not cAMP mediates the PIA-induced potentiation of Ca(2+)-generated phospholipase A2 activation. Although acute phorbol ester activation of protein kinase C induced arachidonic acid release, P2-purinergic and alpha 1-adrenergic stimulation of arachidonic acid release was markedly increased by the protein kinase C down-regulation caused by the phorbol ester. This suggests a suppressive role for protein kinase C in the agonist-induced activation of arachidonic acid release. We conclude that PIA (and perhaps any of the G1-activating agonists) augments an agonist (maybe any of the Ca(2+)-mobilizing agents)-induced arachidonic acid release by activation of Ca(2+)-dependent phospholipase A2 in addition to enhancement of agonist-induced phospholipase C followed by an increase in [Ca2+]i.

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Oxonium ion intermediates in the rearrangement of thebaine

Cited by 76 publications

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Characteristics of lysophospholipase activity expressed by cytosolic phospholipase A₂

Characteristics of lysophospholipase activity expressed by cytosolic phospholipase A₂

Identification of Phosphorylation Sites of Human 85-kDa Cytosolic Phospholipase A2 Expressed in Insect Cells and Present in Human Monocytes

Permissive stimulation of Ca(2+)-induced phospholipase A2 by an adenosine receptor agonist in a pertussis toxin-sensitive manner in FRTL-5 thyroid cells: a new ‘cross-talk’ mechanism in Ca2+ signalling.

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Oxonium ion intermediates in the rearrangement of thebaine

Cited by 76 publications

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Characteristics of lysophospholipase activity expressed by cytosolic phospholipase A2

Characteristics of lysophospholipase activity expressed by cytosolic phospholipase A2

Identification of Phosphorylation Sites of Human 85-kDa Cytosolic Phospholipase A2 Expressed in Insect Cells and Present in Human Monocytes

Permissive stimulation of Ca(2+)-induced phospholipase A2 by an adenosine receptor agonist in a pertussis toxin-sensitive manner in FRTL-5 thyroid cells: a new ‘cross-talk’ mechanism in Ca2+ signalling.

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Characteristics of lysophospholipase activity expressed by cytosolic phospholipase A₂

Characteristics of lysophospholipase activity expressed by cytosolic phospholipase A₂