| |
Reaction
Name | Pathway Name /
Pathway No. | Kf | Kb | Kd | tau | Reagents |
| 1 | Act-PLC-Ca | PLCbeta
Pathway No. 112 | 3
(uM^-1 s^-1) | 1
(s^-1) | Kd(bf) = 0.3333(uM) | - | Substrate:
Ca
PLC
Products:
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. | | 2 | PLC-bind-Gq | PLCbeta
Pathway No. 112 | 2.52
(uM^-1 s^-1) | 1
(s^-1) | Kd(bf) = 0.3968(uM) | - | Substrate:
PLC
G*GTP
Products:
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. | | 3 | PLC-Gq-bind-Ca | PLCbeta
Pathway No. 112 | 30
(uM^-1 s^-1) | 1
(s^-1) | Kd(bf) = 0.0333(uM) | - | Substrate:
PLC-Gq
Ca
Products:
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. | | 4 | Inact-PLC-Gq | PLCbeta
Pathway No. 112 | 1.6667
(s^-1) | 0
(uM^-1 s^-1) | - | - | Substrate:
PLC-Ca-Gq
Products:
PLC-Ca
G*GDP
|
| Rate of 100/min to account for GAP activity of PLC: Biddlecome et al, JBC, 271, 14, 7999-8007, 1996 | | 5 | Act-PLC-by-Gq | PLCbeta
Pathway No. 112 | 25.2
(uM^-1 s^-1) | 1
(s^-1) | Kd(bf) = 0.0397(uM) | - | Substrate:
PLC-Ca
G*GTP
Products:
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 | | 6 | Degrade-DAG | PLCbeta
Pathway No. 112 | 0.15
(s^-1) | 0
(s^-1) | - | - | Substrate:
DAG
Products:
PC
|
| Rate based on basal and activated levels of DAG | | 7 | basal | PLCbeta
Pathway No. 112 | 0.003
(s^-1) | 0
(uM^-1 s^-1) | - | - | Substrate:
PIP2
Products:
DAG
IP3(145)
|
| accounts for other PLC isoforms that contribute to basal levels of IP3 |
and 
color.
indicates that ordering is done according to ascending or descending order.