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Molecule Parameter List for AC2*-Gs | 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 | Synaptic_
Network | 16 | Network |
Shared_Object_Synaptic_Network, PKC, PLA2,
PLCbeta, Gq, MAPK,
Ras, EGFR, Sos,
PLC_g, CaMKII, CaM,
PP1, PP2B, PKA,
AC, CaRegulation | This model is an annotated version of the synaptic signaling network.
The primary reference is Bhalla US and Iyengar R. Science (1999) 283(5400):381-7 but several of the model pathways have been updated.
Bhalla US Biophys J. 2002 Aug;83(2):740-52
Bhalla US J Comput Neurosci. 2002 Jul-Aug;13(1):49-62 |
AC2*-Gs acting as a Molecule in Synaptic_Network Network
| Name | Accession Name | Pathway Name | Initial Conc.
(uM) | Volume
(fL) | Buffered | | AC2*-Gs | Synaptic_
Network
Accession No. : 16 | AC
Pathway No. : 85 | 0 | 1000 | No | | This is the form activated synergistically by phosphorylation as well as Gs binding. |
AC2*-Gs acting as an Enzyme in Synaptic_Network Network
Enzyme Molecule /
Enzyme Activity | Accession Name | Pathway Name | Km (uM) | kcat (s^-1) | Ratio | Enzyme Type | Reagents | AC2*-Gs /
kenz
| Synaptic_
Network
Accession No. : 16 | AC
Pathway No. : 85 | 60 | 54 | 4 | Classical Michaelis-Menten
V = Etot.S.Kcat/Km+S | Substrate
ATP
Product
cAMP
| | The Km is higher here but it is still well below the level of ATP so the enzyme remains saturated. The Vmax is 3x higher than the reference forskolin stimulated form. This scale factor is a compromise between the 2x rise reported by Jacobowitz et al JBC 268(6): 3829-3832 and the 9x rise reported by Yoshimura and Cooper 1993 JBC 268(7):4604-4607. The reference Vmax is from Smigel 1986 JBC 261(4):1976-1982 who has 8.27 umol/min/mg with forskolin stimulated AC. Tang et al JBC 266(13):8595-8603 have an almost identical Vmax of 8 umol/min/mg. This comes to a Vmax of 18/sec. The Km is pretty immaterial since the vast excess of ATP means that the enzyme will normally be saturated. This is a pretty fast enzyme. Note that the saturation of the enzyme means that the regulatory reactions have to involve the complex rather than the free enzyme. |
AC2*-Gs acting as a Product in a reaction in Synaptic_Network 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 | | Gs-bind-AC2* | Synaptic_
Network
Accession No. : 16 | AC
Pathway No. : 85 | 833.28
(uM^-1 s^-1) | 1
(s^-1) | Kd(bf) = 0.0012(uM) | - | Substrate
AC2*
Gs-alpha
Product
AC2*-Gs
| | Various references: Jacobowitz et al JBC 268(6):3829-3892 show that AC2 has a 2x rise in basal activation on phosphorylation, and a 2x rise in forskolin stimulated activation. Yoshimura and Cooper JBC 1993 268(7):4604-4607 say that type II is stimulated 9x over basal. Lustig et al 1993 JBC 268(19):13900-13905 syow a 2x activation by PDBu, and the Gs stimulated response is increased 2x-4x by PDBu. To match all these results with the binding of the unphosphorylated form we use a Kd of 1.2 nM here as compared with the Kd of 2 nM for the unphosphorylated reaction. |
| Database compilation and code copyright (C) 2022, Upinder S. Bhalla and NCBS/TIFR
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