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Molecule Parameter List for L.R.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
L.R.GDP.Gabc participated asMoleculeSum total ofEnzymeSubstrate of an enzymeProduct of an enzymeSubstrate in ReactionProduct in Reaction
No. of occurrences1000012

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.

L.R.GDP.Gabc acting as a Molecule in  
PKA_2003 Network
NameAccession NamePathway NameInitial Conc.
(uM)
Volume
(fL)
Buffered
L.R.GDP.GabcPKA_2003
Accession No. : 47
Gs
Pathway No. : 198
01000No
This is the ternary complex, where all the action happens. There are actually a lot more steps here, including a final step where the GTP binds the L.R.Ga complex and causes the release of GTP.Ga from the L.R. For simplicity this is excluded.

L.R.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
Activate-GsPKA_2003
Accession No. : 47
Gs
Pathway No. : 198
0.025
(s^-1)
0
(uM^-2 s^-1)
--Substrate
L.R.GDP.Gabc

Product
GTP.Ga
Gbg
L.R
This step combines several stages in GTP.Galpha release. From Berstein et al activation is at .35 - 0.7/min From Fay et al Biochem 30 5066-5075 1991 kf = .01/sec. From Brandt and Ross JBC 261(4):1656-1664 (1986) and Ransan et al Biochem J 283(2):519-524 (1992) rates around 2.5/min to 1.5/min are better.

L.R.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
1L-bind-R.GabcPKA_2003
Accession No. : 47
Gs
Pathway No. : 198
5
(uM^-1 s^-1)
0.1
(s^-1)
Kd(bf) = 0.02(uM)-Substrate
L
R.GDP.Gabc

Product
L.R.GDP.Gabc
  From Seifert et al Mol. Pharmacol 56:348-358 (1999) The EC50 for ISO is about 20 nM.
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.



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