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Molecule Parameter List for PLA2-cytosolic

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-cytosolic participated asMoleculeSum total ofEnzymeSubstrate of an enzymeProduct of an enzymeSubstrate in ReactionProduct in Reaction
No. of occurrences1001021

Accession and Pathway Details
Accession NameAccession No.Accession TypePathway Link
  • MAPK-bistability
    -fig1c
  • 35Network
    Shared_Object_MAPK-bistability-fig1c Sos PKC 
    MAPK PLA2 Ras 
    PDGFR 
    Model for figure 1c in Bhalla US et al. Science (2002) 297(5583):1018-23.
    The demo for this figure is available here. This synaptic signaling model is without the MKP-1 feedback, so it is bistable and remains so over long periods.

    PLA2-cytosolic acting as a Molecule in  
    MAPK-bistability-fig1c Network
    NameAccession NamePathway NameInitial Conc.
    (uM)
    Volume
    (fL)
    Buffered
    PLA2-cytosolic
  • MAPK-bistability
    -fig1c

    Accession No. : 35
  • PLA2
    Pathway No. : 183
    0.41000No
    cPLA2 IV form has mol wt of 85 Kd. Glaser et al 1993 TIPS 14:92-98. Calculated cytosolic concentration is ~300 nM from Wijkander and Sundler 1991 Eur J Biochem 202:873 Leslie and Channon 1990 BBA 1045:261 use about 400 nM. Decent match. Use 400 nM.

    PLA2-cytosolic acting as a Substrate for an Enzyme in  
    MAPK-bistability-fig1c Network
    Enzyme Molecule /
    Enzyme Activity
    Accession NamePathway NameKm (uM)kcat (s^-1)RatioEnzyme TypeReagents
    MAPK*  /
    MAPK*
  • MAPK-bistability
    -fig1c

    Accession No. : 35
  • Shared_Object_
    MAPK-bistability
    -fig1c

    Pathway No. : 179
  • 25.641204explicit E-S complexSubstrate
    PLA2-cytosolic

    Product
    PLA2*
    Km = 25uM @ 50 uM ATP and 1mg/ml MBP (huge XS of substrate) Vmax = 4124 pmol/min/ml at a conc of 125 pmol/ml of enz. Numbers are from Sanghera et al JBC 265 pp 52 , 1990. From Nemenoff et al 1993 JBC 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-cytosolic acting as a Substrate in a reaction in  
    MAPK-bistability-fig1c 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
  • MAPK-bistability
    -fig1c

    Accession No. : 35
  • PLA2
    Pathway No. : 183
    1
    (uM^-1 s^-1)
    0.1
    (s^-1)
    Kd(bf) = 0.1(uM)-Substrate
    Ca
    PLA2-cytosolic

    Product
    PLA2-Ca*
      Direct activation of PLA2 by Ca. From Leslie and Channon BBA 1045 (1990) 261-270 fig6 pp267.
    2PIP2-PLA2-act
  • MAPK-bistability
    -fig1c

    Accession No. : 35
  • PLA2
    Pathway No. : 183
    0.0012
    (uM^-1 s^-1)
    0.5
    (s^-1)
    Kd(bf) = 416.6667(uM)-Substrate
    PLA2-cytosolic
    temp-PIP2

    Product
    PIP2-PLA2*
      Activation of PLA2 by PIP2. From Leslie and Channon 1990 BBA 1045:261 the stimulation of PLA2 activity by high PIP2 is 7x. In this model we don't really expect any PIP2 stimulus.

    PLA2-cytosolic acting as a Product in a reaction in  
    MAPK-bistability-fig1c 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
  • dephosphorylate-
    PLA2*
  • MAPK-bistability
    -fig1c

    Accession No. : 35
  • PLA2
    Pathway No. : 183
    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.



    Database compilation and code copyright (C) 2022, Upinder S. Bhalla and NCBS/TIFR
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