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Enzyme List for pathway MAPK (Pathway Number 35)

 Molecule Name/
Site Name 		Km (uM) kcat (1/s)Ratio
(k2/k3)		Enzyme TypeSubstrate Product
1 Enzyme Activity:
act_
transcription

Enzyme Molecule:
nuc_MAPK*		40.00084explicit E-S complexNucleotides
MKP1-RNA
  This is a 'black box' representation of a lot of steps. Constraint provided by determining rate of formation of MKP-1.
2 Enzyme Activity:
MAPKKthr

Enzyme Molecule:
MAPKK*		0.04630.154explicit E-S complexMAPK-tyr
MAPK*
  Rate consts same as for MAPKKtyr.
3 Enzyme Activity:
MAPKKtyr

Enzyme Molecule:
MAPKK*		0.04630.154explicit E-S complexMAPK
MAPK-tyr
  The actual MAPKK is 2 forms from Seger et al JBC 267:20 14373(1992) Vmax = 150nmol/min/mg From Haystead et al FEBS 306(1):17-22 we get Km=46.6nM for at least one of the phosphs. Putting these together: k3=0.15/sec, ratio of 4 to get k2=0.6. k1=0.75/46.6nM=2.7e-5 In terms of Michaelis-Menten rates, Km = 0.046, Vmax = 0.15, ratio = 4.
4 Enzyme Activity:
MKP1*-thr-deph

Enzyme Molecule:
MKP-1**		0.066714Classical Michaelis-Menten
V = Etot.S.Kcat/Km+S		MAPK*
MAPK-tyr
  3 Feb 2000. Same rates as MKP1
5 Enzyme Activity:
MKP1*-tyr-deph

Enzyme Molecule:
MKP-1**		0.066714Classical Michaelis-Menten
V = Etot.S.Kcat/Km+S		MAPK-tyr
MAPK
  3 Feb 2000. Same rates as MKP-1.
6 Enzyme Activity:
Raf*-GTP-Ras.1

Enzyme Molecule:
Raf*-GTP-Ras		0.15910.1054explicit E-S complexMAPKK
MAPKK-ser
  Kinetics are the same as for the craf-1* activity, ie., k1=1.1e-6, k2=.42, k3 =0.105 These are based on Force et al PNAS USA 91 1270-1274 1994. They report Km for MAPKK of 0.8 uM. and a Vmax of ~500 fm/min/ug. These parms cannot reach the observed 4X stimulation of MAPK. So we increase the affinity, ie, raise k1 5x to 5.5e-6 which is equivalent to 5-fold reduction in Km to about 0.16. This is, of course, dependent on the amount of MAPKK present.
7 Enzyme Activity:
Raf*-GTP-Ras.2

Enzyme Molecule:
Raf*-GTP-Ras		0.15910.1054explicit E-S complexMAPKK-ser
MAPKK*
  Same kinetics as other c-raf activated forms. See Force et al PNAS 91 1270-1274 1994.
8 Enzyme Activity:
RGR.1

Enzyme Molecule:
RGR		0.15910.1054explicit E-S complexMAPKK
MAPKK-ser
  Kinetics are the same as for the craf-1* activity, ie., k1=5.5e-6, k2=.42, k3 =0.105 These are based on Force et al PNAS USA 91 1270-1274 1994.
9 Enzyme Activity:
RGR.2

Enzyme Molecule:
RGR		0.15910.1054explicit E-S complexMAPKK-ser
MAPKK*
  Same kinetics as other c-raf activated forms. See Force et al PNAS 91 1270-1274 1994. k1 = 5.5e-6, k2 = .42, k3 = 0.105
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