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Molecule Parameter List for PLC-Ca-Gq

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
PLC-Ca-Gq participated asMoleculeSum total ofEnzymeSubstrate of an enzymeProduct of an enzymeSubstrate in ReactionProduct in Reaction
No. of occurrences1010012

Accession and Pathway Details
Accession NameAccession No.Accession TypePathway Link
  • Ajay_Bhalla_
    2004_PKM_MKP3_
    Tuning
  • 77Network
    Shared_Object_Ajay_Bhalla_2004_PKM_MKP3_Tuning PKC PLA2 
    PLCbeta Ras Gq 
    MAPK EGFR Sos 
    PLC_g CaMKII CaM 
    PP1 PP2B PKA 
    AC MKP3 PKM 
    This model is based on Ajay SM, Bhalla US. Eur J Neurosci. 2004 Nov;20(10):2671-80. This is the feedforward model with MPK3 from figure 8a.

    PLC-Ca-Gq acting as a Molecule in  
    Ajay_Bhalla_2004_PKM_MKP3_Tuning Network
    NameAccession NamePathway NameInitial Conc.
    (uM)
    Volume
    (fL)
    Buffered
    PLC-Ca-Gq
  • Ajay_Bhalla_
    2004_PKM_MKP3_
    Tuning

    Accession No. : 77
  • PLCbeta
    Pathway No. : 332
    01.5No
    This should really be labelled PLC-G*GTP-Ca. This is the activated form of the enzyme. Mahama and Linderman assume that the IP3 precursors are not rate-limiting, but I will include those for completeness as they may be needed later.

    PLC-Ca-Gq acting as an Enzyme in  
    Ajay_Bhalla_2004_PKM_MKP3_Tuning Network
    Enzyme Molecule /
    Enzyme Activity
    Accession NamePathway NameKm (uM)kcat (s^-1)RatioEnzyme TypeReagents
    PLC-Ca-Gq /
    PLCb-Ca-Gq
  • Ajay_Bhalla_
    2004_PKM_MKP3_
    Tuning

    Accession No. : 77
  • PLCbeta
    Pathway No. : 332
    5.00003484explicit E-S complexSubstrate
    PIP2

    Product
    DAG
    IP3
    From Sternweis et al, Phil Trans R Soc Lond 1992, and the values from other refs eg Homma et al JBC 263(14) pp6592 1988 match. k1 = 5e-5/sec k2 = 240/sec; now 120/sec k3 = 60/sec; now 30/sec Note that the wording in Sternweis et al is ambiguous wr. to the Km for Gq vs non-Gq states of PLC. K1 is still a bit too low. Raise to 7e-5 9 Jun 1996: k1 was 0.0002, changed to 5e-5

    PLC-Ca-Gq acting as a Substrate in a reaction in  
    Ajay_Bhalla_2004_PKM_MKP3_Tuning 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
    Inact-PLC-Gq
  • Ajay_Bhalla_
    2004_PKM_MKP3_
    Tuning

    Accession No. : 77
  • PLCbeta
    Pathway No. : 332
    0.0133
    (s^-1)
    0
    (uM^-1 s^-1)
    --Substrate
    PLC-Ca-Gq

    Product
    G*GDP
    PLC-Ca
    This process is assumed to be directly caused by the inactivation of the G*GTP to G*GDP. Hence, kf = .013 /sec = 0.8/min, same as the rate for Inact-G. kb = 0 since this is irreversible. We may be interested in studying the role of PLC as a GAP. If so, the kf would be faster here than in Inact-G

    PLC-Ca-Gq acting as a Product in a reaction in  
    Ajay_Bhalla_2004_PKM_MKP3_Tuning 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
    1Act-PLC-by-Gq
  • Ajay_Bhalla_
    2004_PKM_MKP3_
    Tuning

    Accession No. : 77
  • PLCbeta
    Pathway No. : 332
    25.2
    (uM^-1 s^-1)
    1
    (s^-1)
    Kd(bf) = 0.0397(uM)-Substrate
    G*GTP
    PLC-Ca

    Product
    PLC-Ca-Gq
      Affinity for Gq is > 20 nM (Smrcka et al Science251 804-807 1991) so [Gq].kf = kb so 40nM * 6e5 = kb/kf = 24e3 so kf = 4.2e-5, kb =1
    2PLC-Gq-bind-Ca
  • Ajay_Bhalla_
    2004_PKM_MKP3_
    Tuning

    Accession No. : 77
  • PLCbeta
    Pathway No. : 332
    29.9997
    (uM^-1 s^-1)
    1
    (s^-1)
    Kd(bf) = 0.0333(uM)-Substrate
    Ca
    PLC-Gq

    Product
    PLC-Ca-Gq
      this step has a high affinity for Ca, from Smrcka et al. 0.1uM so kf /kb = 1/6e4 = 1.666e-5:1. See the Act-PLC-by-Gq reac. 11 Jun 1996: Raised kf to 5e-5 based on match to conc-eff curves from Smrcka et al.



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