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Reaction List for pathway PLCbeta (Pathway Number 151) | | 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 reactions is not considered. |
| | Name | Kf | Kb | Kd | tau | Substrate | Product | | 1 |
Act-PLC-by-Gq | 25.2
(uM^-1 s^-1) | 1
(s^-1) | Kd(bf) = 0.0397(uM) | - | PLC-Ca
G*GTP
| PLC-Ca-Gq
| | | Affinity for Gq is > 20 nM (Smrcka et al Science251 804-807 1991) so [Gq].kf = kb so 40nM * 6e5 = kb/kf = 24e3 so kf = 4.2e-5, kb =1 | | 2 |
Act-PLC-Ca | 3
(uM^-1 s^-1) | 1
(s^-1) | Kd(bf) = 0.3333(uM) | - | Ca
PLC
| PLC-Ca
| | | Affinity for Ca = 1uM without AlF, 0.1 with: from Smrcka et al science 251 pp 804-807 1991 so [Ca].kf = kb so kb/kf = 1 * 6e5 = 1/1.66e-6 Assigned affinity to a Kd of 0.333 to maintain balance. | | 3 |
basal | 0.003
(s^-1) | 0
(uM^-1 s^-1) | - | - | PIP2
| DAG
IP3(145)
| | | accounts for other PLC isoforms that contribute to basal levels of IP3 | | 4 |
Degrade-DAG | 0.15
(s^-1) | 0
(s^-1) | - | - | DAG
| PC
| | | Rate based on basal and activated levels of DAG | | 5 |
Inact-PLC-Gq | 1.6667
(s^-1) | 0
(uM^-1 s^-1) | - | - | PLC-Ca-Gq
| PLC-Ca
G*GDP
| | | Rate of 100/min to account for GAP activity of PLC: Biddlecome et al, JBC, 271, 14, 7999-8007, 1996 | | 6 |
PLC-bind-Gq | 2.52
(uM^-1 s^-1) | 1
(s^-1) | Kd(bf) = 0.3968(uM) | - | PLC
G*GTP
| PLC-Gq
| | | this binding does not produce active PLC. This step was needed to implement the described (Smrcka et al) increase in affinity for Ca by PLC once Gq was bound. The tempkin are the same as the binding step for Ca-PLC to Gq. Kd is constrained by detailed balance. | | 7 |
PLC-Gq-bind-Ca | 30
(uM^-1 s^-1) | 1
(s^-1) | Kd(bf) = 0.0333(uM) | - | PLC-Gq
Ca
| PLC-Ca-Gq
| | | this step has a high affinity for Ca, from Smrcka et al. 0.1uM so kf /kb = 1/6e4 = 1.666e-5:1. See the Act-PLC-by-Gq reaction. Raised kf to 5e-5 based on match to conc-eff curves from Smrcka et al. |
Pathway Details Molecule List Enzyme List Reaction List
| Database compilation and code copyright (C) 2022, Upinder S. Bhalla and NCBS/TIFR
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