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Accession Type:
Network
mkp1_feedback_
effects
Shared_Object_
mkp1_feedback_
effects
Sos
PKC
MAPK
PLA2
Ras
 Molecule
 Enzyme
 Reaction
PDGFR

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Reaction List for pathway Ras (Pathway Number 37)

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 KfKbKdtauSubstrateProduct
1 dephosph-GAPkf
(s^-1)
0
(s^-1)
--GAP*
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.
2 dephosph-GEFkf
(s^-1)
0
(s^-1)
--GEF*
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
3 Ras-intrinsic-GT
Pase
kf
(s^-1)
0
(s^-1)
--GTP-Ras
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.


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