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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 |
Accession and Pathway Details | |
| Accession Name | Accession No. | Accession Type | Pathway Link | Synaptic_
Network | 16 | Network |
Shared_Object_Synaptic_Network, PKC, PLA2,
PLCbeta, Gq, MAPK,
Ras, EGFR, Sos,
PLC_g, CaMKII, CaM,
PP1, PP2B, PKA,
AC, CaRegulation | This model is an annotated version of the synaptic signaling network.
The primary reference is Bhalla US and Iyengar R. Science (1999) 283(5400):381-7 but several of the model pathways have been updated.
Bhalla US Biophys J. 2002 Aug;83(2):740-52
Bhalla US J Comput Neurosci. 2002 Jul-Aug;13(1):49-62 |
Sos acting as a Molecule in Synaptic_Network Network
| Name | Accession Name | Pathway Name | Initial Conc.
(uM) | Volume
(fL) | Buffered | | Sos | Synaptic_
Network
Accession No. : 16 | Sos
Pathway No. : 78 | 0.1 | 1000 | No | | 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. |
Sos acting as a Substrate for an Enzyme in Synaptic_Network Network
Enzyme Molecule /
Enzyme Activity | Accession Name | Pathway Name | Km (uM) | kcat (s^-1) | Ratio | Enzyme Type | Reagents | MAPK* /
phosph_Sos | Synaptic_
Network
Accession No. : 16 | Shared_Object_
Synaptic_
Network
Pathway No. : 70 | 2.5641 | 10 | 4 | explicit E-S complex | Substrate
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 Synaptic_Network 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. |
| Name | Accession Name | Pathway Name | Kf | Kb | Kd | tau | Reagents | | Grb2_bind_Sos | Synaptic_
Network
Accession No. : 16 | Sos
Pathway No. : 78 | 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. Porfiri and McCormick JBC 271 also have related data. After comparing with the time-course of 1 min and the efficacy of activation of Ras, settle on Kd of 0.672 which is close to the Chook et al value. |
Sos acting as a Product in a reaction in Synaptic_Network 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. |
| Name | Accession Name | Pathway Name | Kf | Kb | Kd | tau | Reagents | | dephosph_Sos | Synaptic_
Network
Accession No. : 16 | Sos
Pathway No. : 78 | 0.001
(s^-1) | 0
(s^-1) | - | - | Substrate
Sos*
Product
Sos
| | The best 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 |
| Database compilation and code copyright (C) 2022, Upinder S. Bhalla and NCBS/TIFR
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