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Molecule Parameter List for 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

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	4	0	0	0

Accession and Pathway Details

Accession Name	Accession No.	Accession Type	Pathway Link
Ajay_Bhalla_ 2004_PKM_Tuning	76	Network	PKC,  Shared_Object_Ajay_Bhalla_2004_PKM_tuning,  PLA2,   PLCbeta,  Gq,  MAPK,   Ras,  EGFR,  Sos,   PLC_g,  CaMKII,  CaM,   PP1,  PP2B,  PKA,   AC,  PKM
This model is taken from the Ajay SM, Bhalla US. Eur J Neurosci. 2004 Nov;20(10):2671-80. This is the reference feedforward model from Figure 8a.

PIP2 acting as a Molecule in  Ajay_Bhalla_2004_PKM_Tuning Network

Name	Accession Name	Pathway Name	Initial Conc. (uM)	Volume (fL)	Buffered
PIP2	Ajay_Bhalla_ 2004_PKM_Tuning Accession No. : 76	Shared_Object_ Ajay_Bhalla_ 2004_PKM_tuning Pathway No. : 312	10	1.5	Yes

PIP2 acting as a Substrate for an Enzyme in  Ajay_Bhalla_2004_PKM_Tuning Network

	Enzyme Molecule / Enzyme Activity	Accession Name	Pathway Name	Km (uM)	kcat (s^-1)	Ratio	Enzyme Type	Reagents
1	PLC-Ca  / PLC-Ca	Ajay_Bhalla_ 2004_PKM_Tuning Accession No. : 76	PLCbeta Pathway No. : 315	19.8413	10	4	explicit E-S complex	Substrate PIP2 Product DAG IP3
	From Sternweis et al Phil Trans R Soc Lond 1992, also matched by Homma et al. k1 = 1.5e-5, now 4.2e-6 k2 = 70/sec; now 40/sec k3 = 17.5/sec; now 10/sec Note that the wording in Sternweis et al is ambiguous re the Km.
2	PLC-Ca-Gq  / PLCb-Ca-Gq	Ajay_Bhalla_ 2004_PKM_Tuning Accession No. : 76	PLCbeta Pathway No. : 315	5.00003	48	4	explicit E-S complex	Substrate PIP2 Product DAG IP3
	From Sternweis et al, Phil Trans R Soc Lond 1992, and the values from other refs eg Homma et al JBC 263(14) pp6592 1988 match. k1 = 5e-5/sec k2 = 240/sec; now 120/sec k3 = 60/sec; now 30/sec Note that the wording in Sternweis et al is ambiguous wr. to the Km for Gq vs non-Gq states of PLC. K1 is still a bit too low. Raise to 7e-5 9 Jun 1996: k1 was 0.0002, changed to 5e-5
3	Ca.PLC_g  / PIP2_hydrolysis	Ajay_Bhalla_ 2004_PKM_Tuning Accession No. : 76	PLC_g Pathway No. : 321	97.2222	14	4	explicit E-S complex	Substrate PIP2 Product DAG IP3
	Mainly Homma et al JBC 263:14 1988 pp 6592, but these parms are the Ca-stimulated form. It is not clear whether the enzyme is activated by tyrosine phosphorylation at this point or not. Wahl et al JBC 267:15 10447-10456 1992 say that the Ca_stim and phosph form has 7X higher affinity for substrate than control. This is close to Wahl's figure 7, which I am using as reference.
4	Ca.PLC_g*  / PIP2_hydrolysis	Ajay_Bhalla_ 2004_PKM_Tuning Accession No. : 76	PLC_g Pathway No. : 321	19.7917	57	4	explicit E-S complex	Substrate PIP2 Product DAG IP3
	Mainly Homma et al JBC 263:14 1988 pp 6592, but these parms are the Ca-stimulated form. It is not clear whether the enzyme is activated by tyrosine phosphorylation at this point or not. Wahl et al JBC 267:15 10447-10456 1992 say that this has 7X higher affinity for substrate than control.