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Molecule Parameter List for SHC* | 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 | mkp1_feedback_
effects | 4 | Network |
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. |
SHC* acting as a Molecule in mkp1_feedback_effects Network
| Name | Accession Name | Pathway Name | Initial Conc.
(uM) | Volume
(fL) | Buffered | | SHC* | mkp1_feedback_
effects
Accession No. : 4 | PDGFR
Pathway No. : 38 | 0 | 1000 | No | | Phosphorylated form of SHC. Binds to the SoS.Grb2 complex to give the activated GEF form upstream of Ras. |
SHC* acting as a Product of an Enzyme in mkp1_feedback_effects Network
Enzyme Molecule /
Enzyme Activity | Accession Name | Pathway Name | Km (uM) | kcat (s^-1) | Ratio | Enzyme Type | Reagents | L.PDGFR /
phosph_Shc | mkp1_feedback_
effects
Accession No. : 4 | PDGFR
Pathway No. : 38 | 0.833333 | 0.05 | 4 | explicit E-S complex | Substrate
SHC
Product
SHC*
| | Rates from Okada et al JBC 270:35 pp 20737 1995 Km = 0.70 to 0.85 uM, Vmax = 4.4 to 5.0 pmol/min. Unfortunately the amount of enzyme is not known, the prep is only partially purified. Tau phosph is max within 30 sec, falls back within 20 min. Ref: Sasaoka et al JBC 269:51 32621 1994. Use k3 = 0.1 based on this tau. 27 Apr 2001: Lowered k3 to 0.05 to fix conc-effect of SHC phosph by PDGF. This gives results for downstream effects in agreement with other papers, e.g., the Brondello papers. |
SHC* 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. |
| | Name | Accession Name | Pathway Name | Kf | Kb | Kd | tau | Reagents | | 1 | Shc_bind_
Sos.Grb2 | mkp1_feedback_
effects
Accession No. : 4 | Sos
Pathway No. : 33 | 0.5
(uM^-1 s^-1) | 0.1
(s^-1) | Kd(bf) = 0.2(uM) | - | Substrate
SHC*
Sos.Grb2
Product
Shc*.Sos.Grb2
| | | Sasaoka et al JBC 269:51 pp 32621 1994, table on pg 32623 indicates that this pathway accounts for about 50% of the GEF activation. (88% - 39%). Error is large, about 20%. Fig 1 is most useful in constraining rates. Chook et al JBC 271:48 pp 30472, 1996 say that the Kd is 0.2 uM for Shc binding to EGFR. The Kd for Grb direct binding is 0.7, so we'll ignore it. | | 2 | dephosph_Shc | mkp1_feedback_
effects
Accession No. : 4 | PDGFR
Pathway No. : 38 | 0.01
(s^-1) | 0
(s^-1) | - | - | Substrate
SHC*
Product
SHC
| | | Time course of decline of phosph is 20 min from Sasaoka et al 1994 JBC 269(51):32621. Part of this is the turnoff time of the EGFR itself. Lets assume a tau of 10 min for this dephosphorylation as a first pass. 27 Apr 2001: Dephosph too slow, shifts SHC balance over to phosphorylated form. Increase Kf to 0.01. This gives a reasonable overall time-course. |
| Database compilation and code copyright (C) 2022, Upinder S. Bhalla and NCBS/TIFR
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