Studies on the dark/light regulation of maize leaf pyruvate, orthophosphate dikinase by reversible phosphorylation

Budde, Raymond J.A.; Holbrook, Gabriel P.; Chollet, Raymond

doi:10.1016/0003-9861(85)90503-x

Cited by 37 publications

(26 citation statements)

References 24 publications

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“…Four sample tubes (6 x 50 mm), each containing 50 or lOOpug of t-PA, PG or u-PA, were placed in a reaction vial and vacuum-dried using the PICO-TAG Work Station [26]. 200 ~1 of concentrated HCl (37%) and one phenol crystal was added at the bottom of the reaction vial; this reaction vial was purged alternately with nitrogen and after final evacuation to remove O,, its valve was closed, and the reaction vial itself heated in Work Station oven at 106°C for 7 h, subsequently cooled and vacuum-dried to remove excess HCl.…”

Section: S Barluti Et Al Ifebs Letters 363 (1995) 170-174 24 Acidmentioning

confidence: 99%

Phosphorylation of human plasminogen activators and plasminogen

et al. 1995

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Plasminogen (PC), urokinase-type plasminogen activator (u-PA) and tissue-type PA (t-PA) are the main molecules involved in fibrinolysis and in many other physiological and pathological processes. In the present study we report that human t-PA, purified from human melanoma cells, and PG, purified from human plasma, both contain P-Tyr residues, as revealed by immunoblotting analyses with monoclonal anti-P-Tyr antibodies. In addition HPLC amino acid analysis of acid-hydrolyzed t-PA, PG and u-PA, shows that: (i) P-Ser and P-Tyr residues are present in t-PA; (ii) P-Thr and P-Tyr are present in PG; (iii) P-Ser, P-Thr and P-Tyr are present in u-PA. The utilization of monoclonal anti-P-Ser and anti-P-Thr antibodies in immunoblotting experiments has confirmed these data which indicate that phosphorylation is a common feature of PAS and of PG.

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Section: S Barluti Et Al Ifebs Letters 363 (1995) 170-174 24 Acidmentioning

confidence: 99%

Phosphorylation of human plasminogen activators and plasminogen

et al. 1995

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“…The two-step catalytic reaction sequence is shown in the top line of Figure 1. The enzyme is regulated by a lightdependent, DCMU-and photophosphorylation inhibitor-sensitive activation (dephosphorylation) and dark-dependent inactivation (phosphorylation) cycle (1, 3,21). The reactions of this cyclic cascade are catalyzed by a bifunctional stromal regulatory protein (4,7,23) which uses ADP as the substrate for phosphorylation and Pi as acceptor for dephosphorylation of a threonine residue in the active-site domain of dikinase (1, 3, 24) (Fig.…”

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confidence: 99%

“…Several possible modes of regulation can be disallowed: (a) The regulatory protein does not appear to be regulated by covalent modification. When partially purified from light-adapted leaves, it catalyzes both the activation and inactivation of dikinase (3). Similarly, desalted crude extracts from dark-or light-adapted leaves can be used to catalyze either reaction (4).…”

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confidence: 99%

Role of Metabolites in the Reversible Light Activation of Pyruvate, Orthophosphate Dikinase in Zea mays Mesophyll Cells in Vivo

Roeske¹,

Chollet²

1989

Plant Physiol.

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Whole leaf and mesophyll cell concentrations of pyruvate, phosphoenolpyruvate (PEP), ATP, and ADP were determined in Zea mays during the reversible light activation of pyruvate, orthophosphate dikinase in vivo. Mesophyll cell levels of the four metabolites were estimated by extrapolation from values in freeze-quenched leaf samples that were fractionated by differential filtration through nylon mesh nets (adapted from M Stitt, HW Heldt [1985] Planta 164: 179-188). During the 3 minutes required for complete light activation of dikinase, pyruvate levels in the mesophyll cell decreased (from 166 ± 15 to 64 ± 10 nanomoles per milligram of chlorophyll [nmol/mg Chi]) while PEP levels increased (from 31 ± 4 to 68 ± 4 nmol/mg Chi, with a transient burst of 133 ± 16 nmol/mg Chi at 1 minute). Mesophyll cell levels of ATP increased (from 22 ± 4 to 48 ± 3 nmol/mg Chi) and ADP levels decreased (from 16 ± 4 to 7 ± 6 nmol/mg Chl) during the first minute of illumination. Upon darkening of the leaf and inactivation of dikinase, pyruvate levels initially increased in the mesophyll (from 160 ± 30 to a maximum of 625 ± 40 nmol/ mg Chi), and then slowly decreased to about the initial value in the light over an hour. PEP levels dropped (from 176 ± 5 to 47 ± 3 nmol/mg Chi) in the first 3 minutes and remained low for the remainder of the dark period. Mesophyll levels of ATP and ADP rapidly decreased and increased, respectively, about twofold upon darkening. The trends observed for these metabolite levels in the mesophyll cell during the light/dark regulation of pyruvate,orthophosphate dikinase activity suggest that pyruvate and PEP do not play a major role in vivo in regulating the extent of light activation (dephosphorylation) or dark inactivation (ADPdependent threonyl phosphorylation) of dikinase by its bifunctional regulatory protein. While the changes in ADP levels appear qualitatively consistent with a regulatory role for this metabolite in the light activation and dark inactivation of dikinase, they are not of a sufficient magnitude to account completely for the tenfold change in enzyme activity observed in vivo.Pyruvate,orthophosphate dikinase (EC 2.7.9.1) catalyzes the conversion of pyruvate, ATP and Pi to PEP,3 AMP, and

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“…PDC results in inactivation (24), while chloroplastic PDC is apparently not phosphorylated (8). The C4 mesophyll chloroplast enzyme PPDK exhibits a novel ADP-dependent phosphorylation which causes inactivation (1,6,9). Phosphorylation/inactivation of PDC and PPDK has also been established in situ (6,24).…”

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confidence: 99%

“…For the ATP-phosphorylation reactions an ADP-scavenging system composed of phosphocreatine/creatine phosphokinase was also included. When the phosphorylation reactions were quenched for SDS-PAGE, aliquots were also analyzed by poly(ethyleneimine)cellulose-TLC (6) to assess the stability of the 32P-label. These analyses indicated that approximately 7% of the label was randomized between ADP and ATP.…”

mentioning

confidence: 99%