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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 | 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. |
temp-PIP2 acting as a Molecule in mkp1_feedback_effects Network
| Name | Accession Name | Pathway Name | Initial Conc.
(uM) | Volume
(fL) | Buffered | | temp-PIP2 | mkp1_feedback_
effects
Accession No. : 4 | Shared_Object_
mkp1_feedback_
effects
Pathway No. : 32 | 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 PW, Neufeld EJ, Wilson DB. (1984) Cell 37(3):701-703 report a brain concentration of 0.1 - 0.2 mole %. Majerus PW, Connolly TM, Deckmyn H, Ross TS, Bross TE, Ishii H, Bansal VS, Wilson DB. (1986) Science 234(4783):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 CC and Channon JY (1990) Biochim Biophys Acta. 1045(3):261-270] 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 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 | | 1 | PIP2-PLA2-act | mkp1_feedback_
effects
Accession No. : 4 | PLA2
Pathway No. : 36 | 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 | mkp1_feedback_
effects
Accession No. : 4 | PLA2
Pathway No. : 36 | 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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