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Molecule Parameter List for PLA2*

The statistics table lists the distribution of a molecule acting either as a substrate, product, enzyme or as a molecule within the network.
The text color of a molecule is highlighted by color.
Statistics
PLA2* participated asMoleculeSum total ofEnzymeSubstrate of an enzymeProduct of an enzymeSubstrate in ReactionProduct in Reaction
No. of occurrences1000120

Accession and Pathway Details
Accession NameAccession No.Accession TypePathway Link
  • mkp1_feedback_
    effects
  • 4Network
    Shared_Object_mkp1_feedback_effects Sos PKC 
    MAPK PLA2 Ras 
    PDGFR 
    This is a network involving the MAPK-PKC feedback loop with input from the PDGFR in the synapse. The distinctive feature of this model is that it includes MKP-1 induction by MAPK, and the consequent inhibitory regulation of MAPK and the feedback loop. Lots of interesting dynamics arise from this. This link provides supplementary material for the paper Bhalla US et al. Science (2002) 297(5583):1018-23. In the form of several example simulations and demos for the figures in the paper.

    PLA2* acting as a Molecule in  
    mkp1_feedback_effects Network
    NameAccession NamePathway NameInitial Conc.
    (uM)
    Volume
    (fL)
    Buffered
    PLA2*
  • mkp1_feedback_
    effects

    Accession No. : 4
  • PLA2
    Pathway No. : 36
    01000No
    Phosphorylated PLA2. The site differs from the site phosphorylated by PKC. See Nemenoff et al 1993 JBC 268(3):1960-1964

    PLA2* acting as a Product of an Enzyme in  
    mkp1_feedback_effects Network
    Enzyme Molecule /
    Enzyme Activity
    Accession NamePathway NameKm (uM)kcat (s^-1)RatioEnzyme TypeReagents
    MAPK*  /
    MAPK*
  • mkp1_feedback_
    effects

    Accession No. : 4
  • Shared_Object_
    mkp1_feedback_
    effects

    Pathway No. : 32
  • 25.641204explicit E-S complexSubstrate
    PLA2-cytosolic

    Product
    PLA2*
    Km for MBP = 25 uM at 50 uM ATP, Km for ATP = 58 uM at 1mg/ml MBP (huge excess of substrate), Vmax = 4124 pmol/min/ml at a concentartion of 125 pmol/ml of enzyme. Numbers are from pp. 54 Sanghera JS, Paddon HB, Bader SA, Pelech SL. (1990) J Biol Chem. 265(1):52-7. From Nemenoff RA, Winitz S, Qian NX, Van Putten V, Johnson GL, Heasley LE. (1993) J Biol Chem. 268(3):1960-1964 - using Sanghera's 1e-4 ratio of MAPK to protein, we get k3 = 7/sec from 1000 pmol/min/mg total protein in fig 5 I take the Vmax to be higher for PLA2 given the fold activation of PLA2 by MAPK. This is actually a balance term between MAPK and the dephosphorylation step.

    PLA2* acting as a Substrate in a reaction in  
    mkp1_feedback_effects Network
    Kd is calculated only for second order reactions, like nA+nB <->nC or nA<->nC+nD, where n is number and A,B,C,D are molecules, where as for first order reactions Keq is calculated. Kd for higher order reaction are not consider.
     NameAccession NamePathway NameKfKbKdtauReagents
    1PLA2*-Ca-act
  • mkp1_feedback_
    effects

    Accession No. : 4
  • PLA2
    Pathway No. : 36
    6
    (uM^-1 s^-1)
    0.1
    (s^-1)
    Kd(bf) = 0.0167(uM)-Substrate
    Ca
    PLA2*

    Product
    PLA2*-Ca
      Nemenoff et al 1993 JBC 268:1960 report a 2X to 4x activation of PLA2 by MAPK, which seems dependent on Ca as well. This reaction represents this activation. Rates are scaled to give appropriate fold activation.
    2
  • dephosphorylate-
    PLA2*
  • mkp1_feedback_
    effects

    Accession No. : 4
  • PLA2
    Pathway No. : 36
    0.17
    (s^-1)
    0
    (s^-1)
    --Substrate
    PLA2*

    Product
    PLA2-cytosolic
      Dephosphorylation reaction to balance MAPK phosphorylation of PLA2. This is probably mediated by PP2A. Rates determined to keep the balance of phosphorylated and non-phosphorylated PLA2 reasonable. The constraining factor is the fold activation of PLA2 by MAPK.



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