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John F. Allen - One of the best experts on this subject based on the ideXlab platform.

  • Effects of synthetic peptides on thylakoid Phosphoprotein Phosphatase reactions
    Physiologia Plantarum, 1995
    Co-Authors: Lüling Cheng, Dalibor Stys, John F. Allen
    Abstract:

    A synthetic peptide analogue of the phosphorylation site of LHC II, when phosphorylated by thylakoid membranes, served as a substrate for the thylakoid Phosphoprotein Phosphatase. The phosphopeptide became dephosphorylated at a low rate, comparable to that of the 9 kDa Phosphoprotein. Phospho-LHC II itself became dephosphorylated much more rapidly, at a rate unaffected by endogenous phosphorylation of the peptide. Endogenous phosphorylation of the peptide was also without effect on other thylakoid protein phosphorylation and dephosphorylation reactions. In contrast, dephosphorylation of many thylakoid Phosphoproteins was inhibited by addition of a pure, chemically-synthesised phosphopeptide analogue of phospho-LHC II

  • Substrate specificity and kinetics of thylakoid Phosphoprotein Phosphatase reactions
    Biochimica et Biophysica Acta, 1994
    Co-Authors: Lüling Cheng, Michael D. Spangfort, John F. Allen
    Abstract:

    Abstract A synthetic 15-amino-acid phosphopeptide analogue of an N-terminal phosphorylated segment of LHC II was found to inhibit dephosphorylation not only of phospho-LHC II but of all other thylakoid Phosphoproteins resolved by phosphorimaging. The results suggest that structural features required for recognition of the Phosphoprotein Phosphatase are common to different thylakoid Phosphoproteins as well as to the phosphopeptide itself: at least one thylakoid Phosphoprotein Phosphatase exhibits a broad substrate specificity. Dephosphorylation reaction rates of all 13 thylakoid Phosphoproteins were determined, and the dephosphorylation half-times were found to range from 7 min to more than 180 min. Most of the Phosphoprotein dephosphorylation reactions were partially inhibited by NaF, and were insensitive to antimycin A and okadaic acid. Nevertheless, both antimycin A and NaF stimulated the phosphorylation of LHC II and the 9 kDa protein. Possible reasons for differences in sensitivity to these inhibitors are discussed.

Thomas M. Chiang - One of the best experts on this subject based on the ideXlab platform.

  • Phosphorylation–Dephosphorylation States at Different Sites Affect Phosphoprotein Phosphatase 1 Activity
    Thrombosis Research, 1998
    Co-Authors: Thomas M. Chiang
    Abstract:

    Abstract We have previously reported that the binding of type I collagen to its receptor initiates platelet aggregation involving Phosphoprotein Phosphatase 1 (PP 1), which coprecipitates with the 65-kDa platelet type I collagen receptor. Phosphorylation of the anti-PP1 precipitation PP1 decreases its enzyme activity. In the present investigation, the mechanism of the decreased enzyme activity was studied by examining the phosphorylation of PP 1 on serine/threonine or tyrosine residues. Phosphoamino acid analysis of the PP 1 indicates that serine, threone, and tyrosine can all be phosphorylated. We find that the activity of PP 1 decreases with serine/threonine phosphorylation but that phosphorylation of tyrosine residue activates enzyme activity. These results indicate that the activity of platelet Phosphoprotein Phosphatase 1 is controlled by phosphorylation and dephosphorylation states at multiple, different site(s).

  • phosphorylation dephosphorylation states at different sites affect Phosphoprotein Phosphatase 1 activity
    Thrombosis Research, 1998
    Co-Authors: Thomas M. Chiang
    Abstract:

    We have previously reported that the binding of type I collagen to its receptor initiates platelet aggregation involving Phosphoprotein Phosphatase 1 (PP 1), which coprecipitates with the 65-kDa platelet type I collagen receptor. Phosphorylation of the anti-PP1 precipitation PP1 decreases its enzyme activity. In the present investigation, the mechanism of the decreased enzyme activity was studied by examining the phosphorylation of PP 1 on serine/threonine or tyrosine residues. Phosphoamino acid analysis of the PP 1 indicates that serine, threonine, and tyrosine can all be phosphorylated. We find that the activity of PP 1 decreases with serine/threonine phosphorylation but that phosphorylation of tyrosine residue activates enzyme activity. These results indicate that the activity of platelet Phosphoprotein Phosphatase 1 is controlled by phosphorylation and dephosphorylation states at multiple, different site(s).

Lüling Cheng - One of the best experts on this subject based on the ideXlab platform.

  • Effects of synthetic peptides on thylakoid Phosphoprotein Phosphatase reactions
    Physiologia Plantarum, 1995
    Co-Authors: Lüling Cheng, Dalibor Stys, John F. Allen
    Abstract:

    A synthetic peptide analogue of the phosphorylation site of LHC II, when phosphorylated by thylakoid membranes, served as a substrate for the thylakoid Phosphoprotein Phosphatase. The phosphopeptide became dephosphorylated at a low rate, comparable to that of the 9 kDa Phosphoprotein. Phospho-LHC II itself became dephosphorylated much more rapidly, at a rate unaffected by endogenous phosphorylation of the peptide. Endogenous phosphorylation of the peptide was also without effect on other thylakoid protein phosphorylation and dephosphorylation reactions. In contrast, dephosphorylation of many thylakoid Phosphoproteins was inhibited by addition of a pure, chemically-synthesised phosphopeptide analogue of phospho-LHC II

  • Substrate specificity and kinetics of thylakoid Phosphoprotein Phosphatase reactions
    Biochimica et Biophysica Acta, 1994
    Co-Authors: Lüling Cheng, Michael D. Spangfort, John F. Allen
    Abstract:

    Abstract A synthetic 15-amino-acid phosphopeptide analogue of an N-terminal phosphorylated segment of LHC II was found to inhibit dephosphorylation not only of phospho-LHC II but of all other thylakoid Phosphoproteins resolved by phosphorimaging. The results suggest that structural features required for recognition of the Phosphoprotein Phosphatase are common to different thylakoid Phosphoproteins as well as to the phosphopeptide itself: at least one thylakoid Phosphoprotein Phosphatase exhibits a broad substrate specificity. Dephosphorylation reaction rates of all 13 thylakoid Phosphoproteins were determined, and the dephosphorylation half-times were found to range from 7 min to more than 180 min. Most of the Phosphoprotein dephosphorylation reactions were partially inhibited by NaF, and were insensitive to antimycin A and okadaic acid. Nevertheless, both antimycin A and NaF stimulated the phosphorylation of LHC II and the 9 kDa protein. Possible reasons for differences in sensitivity to these inhibitors are discussed.

Craig C Malbon - One of the best experts on this subject based on the ideXlab platform.

  • Phosphoprotein Phosphatase-2A docks to Dishevelled and counterregulates Wnt3a/β-catenin signaling
    Journal of Molecular Signaling, 2007
    Co-Authors: Noriko Yokoyama, Craig C Malbon
    Abstract:

    Background Wnt3a stimulates cellular trafficking of key signaling elements ( e.g ., Axin, Dishevelled-2, β-catenin, and glycogen synthase kinase-3β) and primitive endoderm formation in mouse F9 embryonic teratocarcinoma cells. Results The role of Phosphoprotein Phosphatase-2A in signaling of the Wnt/β-catenin/Lef-Tcf-sensitive gene activation pathway was investigated. Wnt3a action attenuates Phosphoprotein Phosphatase-2A activity and stimulates the Lef/Tcf-sensitive gene transcription. Inhibiting Phosphoprotein Phosphatase-2A by okadaic acid, by treatment with siRNA (targeting the C-subunit of the enzyme), or by expression of SV40 small t antigen mimics Wnt3a action, increasing the cellular abundance of Axin and phospho-glycogen synthase kinase-3β as well as the trafficking of signaling elements in the Wnt/β-catenin pathway. Although mimicking effects of Wnt3a on the cellular abundance and trafficking of key signaling elements in the Wnt canonical pathway, suppression of Phosphatase-2A alone did not provoke activation of the Lef/Tcf-sensitive transcriptional response, but did potentiate its activation by Wnt3a. Phosphoprotein Phosphatase-2A and the scaffold Phosphoprotein Dishevelled-2 display similarities in cellular trafficking in response to either Wnt3a or suppression of the Phosphatase. A docking site for Phosphoprotein Phosphatase-2A in the DEP domain of Dishevelled-2 was identified. Conclusion In current study, we showed new roles of Phosphoprotein Phosphatase-2A in Wnt/β-catenin signaling pathway: effect on protein expression, effect on protein trafficking, retention of molecules in subcellular compartments, and regulation of enzymatic activity of several key players. Docking of Phosphoprotein Phosphatase-2A by Dishevelled-2 suppresses Phosphatase activity and explains in part the central role of this Phosphatase in the counterregulation of the Wnt/β-catenin signaling pathway.

  • Phosphoprotein Phosphatase 2a docks to dishevelled and counterregulates wnt3a β catenin signaling
    Journal of Molecular Signaling, 2007
    Co-Authors: Noriko Yokoyama, Craig C Malbon
    Abstract:

    Background: Wnt3a stimulates cellular trafficking of key signaling elements (e.g., Axin, Dishevelled-2, β-catenin, and glycogen synthase kinase-3β) and primitive endoderm formation in mouse F9 embryonic teratocarcinoma cells. Results: The role of Phosphoprotein Phosphatase-2A in signaling of the Wnt/β-catenin/Lef-Tcfsensitive gene activation pathway was investigated. Wnt3a action attenuates Phosphoprotein Phosphatase-2A activity and stimulates the Lef/Tcf-sensitive gene transcription. Inhibiting Phosphoprotein Phosphatase-2A by okadaic acid, by treatment with siRNA (targeting the Csubunit of the enzyme), or by expression of SV40 small t antigen mimics Wnt3a action, increasing the cellular abundance of Axin and phospho-glycogen synthase kinase-3β as well as the trafficking of signaling elements in the Wnt/β-catenin pathway. Although mimicking effects of Wnt3a on the cellular abundance and trafficking of key signaling elements in the Wnt canonical pathway, suppression of Phosphatase-2A alone did not provoke activation of the Lef/Tcf-sensitive transcriptional response, but did potentiate its activation by Wnt3a. Phosphoprotein Phosphatase- 2A and the scaffold Phosphoprotein Dishevelled-2 display similarities in cellular trafficking in response to either Wnt3a or suppression of the Phosphatase. A docking site for Phosphoprotein Phosphatase-2A in the DEP domain of Dishevelled-2 was identified. Conclusion: In current study, we showed new roles of Phosphoprotein Phosphatase-2A in Wnt/ β-catenin signaling pathway: effect on protein expression, effect on protein trafficking, retention of molecules in subcellular compartments, and regulation of enzymatic activity of several key players. Docking of Phosphoprotein Phosphatase-2A by Dishevelled-2 suppresses Phosphatase activity and explains in part the central role of this Phosphatase in the counterregulation of the Wnt/β-catenin signaling pathway.

Noriko Yokoyama - One of the best experts on this subject based on the ideXlab platform.

  • Phosphoprotein Phosphatase-2A docks to Dishevelled and counterregulates Wnt3a/β-catenin signaling
    Journal of Molecular Signaling, 2007
    Co-Authors: Noriko Yokoyama, Craig C Malbon
    Abstract:

    Background Wnt3a stimulates cellular trafficking of key signaling elements ( e.g ., Axin, Dishevelled-2, β-catenin, and glycogen synthase kinase-3β) and primitive endoderm formation in mouse F9 embryonic teratocarcinoma cells. Results The role of Phosphoprotein Phosphatase-2A in signaling of the Wnt/β-catenin/Lef-Tcf-sensitive gene activation pathway was investigated. Wnt3a action attenuates Phosphoprotein Phosphatase-2A activity and stimulates the Lef/Tcf-sensitive gene transcription. Inhibiting Phosphoprotein Phosphatase-2A by okadaic acid, by treatment with siRNA (targeting the C-subunit of the enzyme), or by expression of SV40 small t antigen mimics Wnt3a action, increasing the cellular abundance of Axin and phospho-glycogen synthase kinase-3β as well as the trafficking of signaling elements in the Wnt/β-catenin pathway. Although mimicking effects of Wnt3a on the cellular abundance and trafficking of key signaling elements in the Wnt canonical pathway, suppression of Phosphatase-2A alone did not provoke activation of the Lef/Tcf-sensitive transcriptional response, but did potentiate its activation by Wnt3a. Phosphoprotein Phosphatase-2A and the scaffold Phosphoprotein Dishevelled-2 display similarities in cellular trafficking in response to either Wnt3a or suppression of the Phosphatase. A docking site for Phosphoprotein Phosphatase-2A in the DEP domain of Dishevelled-2 was identified. Conclusion In current study, we showed new roles of Phosphoprotein Phosphatase-2A in Wnt/β-catenin signaling pathway: effect on protein expression, effect on protein trafficking, retention of molecules in subcellular compartments, and regulation of enzymatic activity of several key players. Docking of Phosphoprotein Phosphatase-2A by Dishevelled-2 suppresses Phosphatase activity and explains in part the central role of this Phosphatase in the counterregulation of the Wnt/β-catenin signaling pathway.

  • Phosphoprotein Phosphatase 2a docks to dishevelled and counterregulates wnt3a β catenin signaling
    Journal of Molecular Signaling, 2007
    Co-Authors: Noriko Yokoyama, Craig C Malbon
    Abstract:

    Background: Wnt3a stimulates cellular trafficking of key signaling elements (e.g., Axin, Dishevelled-2, β-catenin, and glycogen synthase kinase-3β) and primitive endoderm formation in mouse F9 embryonic teratocarcinoma cells. Results: The role of Phosphoprotein Phosphatase-2A in signaling of the Wnt/β-catenin/Lef-Tcfsensitive gene activation pathway was investigated. Wnt3a action attenuates Phosphoprotein Phosphatase-2A activity and stimulates the Lef/Tcf-sensitive gene transcription. Inhibiting Phosphoprotein Phosphatase-2A by okadaic acid, by treatment with siRNA (targeting the Csubunit of the enzyme), or by expression of SV40 small t antigen mimics Wnt3a action, increasing the cellular abundance of Axin and phospho-glycogen synthase kinase-3β as well as the trafficking of signaling elements in the Wnt/β-catenin pathway. Although mimicking effects of Wnt3a on the cellular abundance and trafficking of key signaling elements in the Wnt canonical pathway, suppression of Phosphatase-2A alone did not provoke activation of the Lef/Tcf-sensitive transcriptional response, but did potentiate its activation by Wnt3a. Phosphoprotein Phosphatase- 2A and the scaffold Phosphoprotein Dishevelled-2 display similarities in cellular trafficking in response to either Wnt3a or suppression of the Phosphatase. A docking site for Phosphoprotein Phosphatase-2A in the DEP domain of Dishevelled-2 was identified. Conclusion: In current study, we showed new roles of Phosphoprotein Phosphatase-2A in Wnt/ β-catenin signaling pathway: effect on protein expression, effect on protein trafficking, retention of molecules in subcellular compartments, and regulation of enzymatic activity of several key players. Docking of Phosphoprotein Phosphatase-2A by Dishevelled-2 suppresses Phosphatase activity and explains in part the central role of this Phosphatase in the counterregulation of the Wnt/β-catenin signaling pathway.