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Molecule Parameter List for GAP | 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. |
GAP acting as a Molecule in mkp1_feedback_effects Network
| Name | Accession Name | Pathway Name | Initial Conc.
(uM) | Volume
(fL) | Buffered | | GAP | mkp1_feedback_
effects
Accession No. : 4 | Ras
Pathway No. : 37 | 0.002 | 1000 | No | | GTPase-activating proteins. See Boguski and McCormick 1993 Nature 366:643-654 Turn off Ras by helping to hydrolyze bound GTP. This one is probably NF1, ie., Neurofibromin as it is inhibited by AA and lipids, and expressed in neural cells. p120-GAP is also a possible candidate, but is less regulated. Both may exist at similar levels. See Eccleston et al JBC 268(36) pp27012-19 Level=.002 |
GAP acting as an Enzyme in mkp1_feedback_effects Network
Enzyme Molecule /
Enzyme Activity | Accession Name | Pathway Name | Km (uM) | kcat (s^-1) | Ratio | Enzyme Type | Reagents | GAP /
GAP-inact-ras
| mkp1_feedback_
effects
Accession No. : 4 | Ras
Pathway No. : 37 | 1.0104 | 10 | 100 | explicit E-S complex | Substrate
GTP-Ras
Product
GDP-Ras
| | From Eccleston et al JBC 268(36)pp27012-19 get Kd < 2uM, kcat - 10/sec From Martin et al Cell 63 843-849 1990 get Kd ~ 250 nM, kcat = 20/min I will go with the Eccleston figures as there are good error bars (10%). The two sets of values are reasonably close. k1 = 1.666e-3/sec, k2 = 1000/sec, k3 = 10/sec (note k3 is rate-limiting) This is one of the rare cases where we have direct info on the k3 being rate-limiting. Hence the ratio I use for the k2:k3 rates is 100 rather than the usual 4. |
GAP acting as a Substrate for an Enzyme in mkp1_feedback_effects Network
GAP acting as a Product 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 | | dephosph-GAP | mkp1_feedback_
effects
Accession No. : 4 | Ras
Pathway No. : 37 | 0.1
(s^-1) | 0
(s^-1) | - | - | Substrate
GAP*
Product
GAP
| | Assume a reasonably good rate for dephosphorylating it, 0.1/sec. This fits well with resting levels of active kinase and the degree of activation as well as time-course of turnoff of Ras activation, but data is quite indirect. |
| Database compilation and code copyright (C) 2022, Upinder S. Bhalla and NCBS/TIFR
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