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Molecule Parameter List for Sos

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
Sos participated asMoleculeSum total ofEnzymeSubstrate of an enzymeProduct of an enzymeSubstrate in ReactionProduct in Reaction
No. of occurrences1001011

Accession and Pathway Details
Accession NameAccession No.Accession TypePathway Link
EGFR_MAPK58Network
Shared_Object_EGFR_MAPK MAPK Ras 
EGFR Sos 
Model of MAPK activation by EGFR in the synapse. Demonstration programs using this model are available here.
Primary citation:Bhalla US. Biophys J. (2004) 87(2):745-53.

Sos acting as a Molecule in  
EGFR_MAPK Network
NameAccession NamePathway NameInitial Conc.
(uM)
Volume
(fL)
Buffered
SosEGFR_MAPK
Accession No. : 58
Sos
Pathway No. : 233
0.11000No
I have tried using low (0.02 uM) initial concs, but these give a very flat response to EGF stim although the overall activation of Ras is not too bad. I am reverting to 0.1 because we expect a sharp initial response, followed by a decline. Sep 17 1997: The transient activation curve looks better with [Sos] = 0.05. Apr 26 1998: Some error there, it is better where it was at 0.1

Sos acting as a Substrate for an Enzyme in  
EGFR_MAPK Network
Enzyme Molecule /
Enzyme Activity
Accession NamePathway NameKm (uM)kcat (s^-1)RatioEnzyme TypeReagents
MAPK*  /
phosph_Sos
EGFR_MAPK
Accession No. : 58
  • Shared_Object_
    EGFR_MAPK

    Pathway No. : 229
  • 2.5641104explicit E-S complexSubstrate
    Sos

    Product
    Sos*
    See Porfiri and McCormick JBC 271:10 pp5871 1996 for the existence of this step. We'll take the rates from the ones used for the phosph of Raf by MAPK. Sep 17 1997: The transient activation curve matches better with k1 up by 10 x.

    Sos acting as a Substrate in a reaction in  
    EGFR_MAPK 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
    Grb2_bind_SosEGFR_MAPK
    Accession No. : 58
    Sos
    Pathway No. : 233
    0.025
    (uM^-1 s^-1)
    0.0168
    (s^-1)
    Kd(bf) = 0.672(uM)-Substrate
    Grb2
    Sos

    Product
    Sos.Grb2
    As there are 2 SH3 domains, this reaction could be 2nd order. I have a Kd of 22 uM from peptide binding (Lemmon et al JBC 269:50 pg 31653). However, Chook et al JBC 271:48 pg30472 say it is 0.4uM with purified proteins, so we believe them. They say it is 1:1 binding.

    Sos acting as a Product in a reaction in  
    EGFR_MAPK 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
    dephosph_SosEGFR_MAPK
    Accession No. : 58
    Sos
    Pathway No. : 233
    0.001
    (s^-1)
    0
    (s^-1)
    --Substrate
    Sos*

    Product
    Sos
    The only clue I have to these rates is from the time courses of the EGF activation, which is around 1 to 5 min. The dephosph would be expected to be of the same order, perhaps a bit longer. Lets use 0.002 which is about 8 min. Sep 17: The transient activation curve matches better with kf = 0.001



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