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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

SHC* participated as	Molecule	Sum total of	Enzyme	Substrate of an enzyme	Product of an enzyme	Substrate in Reaction	Product in Reaction
No. of occurrences	1	0	0	0	1	2	0

Accession and Pathway Details

Accession Name	Accession No.	Accession Type	Pathway Link
MAPK-bistability -fig1c	35	Network	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.

SHC* acting as a Molecule in MAPK-bistability-fig1c Network

Name	Accession Name	Pathway Name	Initial Conc. (uM)	Volume (fL)	Buffered
SHC*	MAPK-bistability -fig1c Accession No. : 35	PDGFR Pathway No. : 185	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 MAPK-bistability-fig1c Network

Enzyme Molecule / Enzyme Activity	Accession Name	Pathway Name	Km (uM)	kcat (s^-1)	Ratio	Enzyme Type	Reagents
L.PDGFR / phosph_Shc	MAPK-bistability -fig1c Accession No. : 35	PDGFR Pathway No. : 185	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 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.

	Name	Accession Name	Pathway Name	Kf	Kb	Kd	tau	Reagents
1	Shc_bind_ Sos.Grb2	MAPK-bistability -fig1c Accession No. : 35	Sos Pathway No. : 180	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	MAPK-bistability -fig1c Accession No. : 35	PDGFR Pathway No. : 185	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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