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Molecule Parameter List for GDP.Gabc

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
GDP.Gabc participated asMoleculeSum total ofEnzymeSubstrate of an enzymeProduct of an enzymeSubstrate in ReactionProduct in Reaction
No. of occurrences1000021

Accession and Pathway Details
Accession NameAccession No.Accession TypePathway Link
PKA_200347Network
Shared_Object_PKA_2003 PKA AC 
Gs 
This model consists of receptor-ligand interaction, G-protein activation, Adenylyl cyclase mediated formation of cAMP and activation of PKA in the neuron. Demonstration programs using this model described in Bhalla US. (2004) Biophys J. 87(2):733-44 to generate a dose-response curve using stochastic calculations are available here.

GDP.Gabc acting as a Molecule in  
PKA_2003 Network
NameAccession NamePathway NameInitial Conc.
(uM)
Volume
(fL)
Buffered
GDP.GabcPKA_2003
Accession No. : 47
Gs
Pathway No. : 198
11000No
The resting state of Gs: GDP bound to trimer. From Pang and Sternweis JBC 265:30 18707-12 1990 we get conc est 1.6 uM to 0.8 uM. We'll use 1 uM.

GDP.Gabc acting as a Substrate in a reaction in  
PKA_2003 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
1R-bind-GabcPKA_2003
Accession No. : 47
Gs
Pathway No. : 198
0.2
(uM^-1 s^-1)
0.1
(s^-1)
Kd(bf) = 0.5(uM)-Substrate
GDP.Gabc
R

Product
R.GDP.Gabc
  Receptor binding to Gs. Scale it to the same slow rates described by Fay et al for L.R to L.R.G. From detailed balance, Kd is 50.
2L.R-bind-GabcPKA_2003
Accession No. : 47
Gs
Pathway No. : 198
10.0002
(uM^-1 s^-1)
0.1
(s^-1)
Kd(bf) = 0.01(uM)-Substrate
GDP.Gabc
L.R

Product
L.R.GDP.Gabc
  See Fay et al Biochem 30 5066-5075 1991. kf is 0.01/sec but does not account for Gs levels. kb is 0.0001/sec. The fraction of RG is about 50%, so we can estimate Kd at about the same as for Gs basal levels. This rate has to be faster since it has to feed GTP.Ga into the system faster than the GTPase. Waldhoer et al Mol Pharmacol 53:808-818 1988 say affinity for A1adenosine/Gi is 10 nM.

GDP.Gabc acting as a Product in a reaction in  
PKA_2003 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
Trimerize-GsPKA_2003
Accession No. : 47
Gs
Pathway No. : 198
6
(uM^-1 s^-1)
0
(s^-1)
--Substrate
GDP.Ga
Gbg

Product
GDP.Gabc
Negligible back-reaction.



Database compilation and code copyright (C) 2022, Upinder S. Bhalla and NCBS/TIFR
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