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Molecule Parameter List for temp-PIP2 | 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 |
| temp-PIP2 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 | 0 | 2 | 0 |
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 |
temp-PIP2 acting as a Molecule in Synaptic_Network Network
| Name | Accession Name | Pathway Name | Initial Conc.
(uM) | Volume
(fL) | Buffered | | temp-PIP2 | Synaptic_
Network
Accession No. : 16 | Shared_Object_
Synaptic_
Network
Pathway No. : 70 | 2.5 | 1000 | Yes | | This is a steady PIP2 input to PLA2. The sensitivity of PLA2 to PIP2 discussed below does not match with the reported free levels which are used by the phosphlipase Cs. My understanding is that there may be different pools of PIP2 available for stimulating PLA2 as opposed to being substrates for PLCs. For that reason I have given this PIP2 pool a separate identity. As it is a steady input this is not a problem in this model. Majerus et al Cell 37:701-703 report a brain concentration of 0.1 - 0.2 mole % Majerus et al Science 234:1519-1526 report a huge range of concentrations: from 1 to 10% of PI content, which is in turn 2-8% of cell lipid. This gives 2e-4 to 8e-3 of cell lipid. In concentrations in total volume of cell (a somewhat strange number given the compartmental considerations) this comes to anywhere from 4 uM to 200 uM. PLA2 is stim 7x by PIP2 (Leslie and Channon BBA 1045:261(1990) Leslie and Channon say PIP2 is present at 0.1 - 0.2mol% range in membs, so I'll use a value at the lower end of the scale for basal PIP2. |
temp-PIP2 acting as a Substrate 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 | | 1 | PIP2-PLA2-act | Synaptic_
Network
Accession No. : 16 | PLA2
Pathway No. : 72 | 0.0012
(uM^-1 s^-1) | 0.5
(s^-1) | Kd(bf) = 416.6667(uM) | - | Substrate
PLA2-cytosolic
temp-PIP2
Product
PIP2-PLA2*
| | | Activation of PLA2 by PIP2. From Leslie and Channon 1990 BBA 1045:261 the stimulation of PLA2 activity by high PIP2 is 7x. In this model we don't really expect any PIP2 stimulus. | | 2 | PIP2-Ca-PLA2-act | Synaptic_
Network
Accession No. : 16 | PLA2
Pathway No. : 72 | 0.012
(uM^-1 s^-1) | 0.1
(s^-1) | Kd(bf) = 8.3333(uM) | - | Substrate
PLA2-Ca*
temp-PIP2
Product
PIP2-Ca-PLA2*
| | | Synergistic activation of PLA2 by Ca and PIP2. Again from Leslie and Channon 1990 BBA 1045:261 |
| Database compilation and code copyright (C) 2022, Upinder S. Bhalla and NCBS/TIFR
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