| |
Reaction
Name | Pathway Name /
Pathway No. | Kf | Kb | Kd | tau | Reagents |
| 1 | dephosph-GEF | Ras
Pathway No. 37 | 0.1
(s^-1) | 0
(s^-1) | - | - | Substrate:
GEF*
Products:
inact-GEF
|
| This rate is based on the known ratio of GDP-Ras to GTP-Ras. Basal: Ras.GTP = 7% Stimulated 15% Time course is within 10 min, probably much faster as not all early data points are there. See Gibbs et al JBC 265(33):20437-20422 | | 2 | Ras-intrinsic-GT
Pase | Ras
Pathway No. 37 | 0.0001
(s^-1) | 0
(s^-1) | - | - | Substrate:
GTP-Ras
Products:
GDP-Ras
|
| This is extremely slow (kf = 1e-4), but it is significant as so little GAP actually gets complexed with it that the total GTP turnover rises only by 2-3 X (see Gibbs et al, JBC 265(33) 20437-20422) and Eccleston et al JBC 268(36) 27012-27019 There is no back reaction as we assume this to be a regular irreversible Michaelis-Menten zeroth order hydrolysis. | | 3 | dephosph-GAP | Ras
Pathway No. 37 | 0.1
(s^-1) | 0
(s^-1) | - | - | Substrate:
GAP*
Products:
GAP
|
| Assume a reasonably good rate for dephosphorylating it, 0.1/sec. This fits well with resting levels of active kinase and the degree of activation as well as time-course of turnoff of Ras activation, but data is quite indirect. |
and 
color.
indicates that ordering is done according to ascending or descending order.