Enter a Search String

Special character and space not allowed in the query term. Search string should be at least 2 characters long.
Search in: Search for Match By

Enzyme List for pathway MAPK (Pathway Number 75)

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

Enzyme Molecule:
MAPKK*		0.04630.154explicit E-S complexMAPK-tyr
MAPK*
  Rate consts same as for MAPKKtyr.
2 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.
3 Enzyme Activity:
Raf-GTP-Ras*.1

Enzyme Molecule:
Raf-GTP-Ras*		0.15910.1054explicit E-S complexMAPKK
MAPKK-ser
  This enzyme activity refers to the complex of phosphorylated Raf and activated Ras. Starting point for 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 who report a Km of 0.8 uM and Vmax of ~500 fm/min/ug for MAPKK. These parms cannot reach the observed 4X stim of MAPK. So we increase the affinity, ie, raise k1 5X to 5.5e-6 which is equivalent to a 5x reduction in Km to about 0.16.
4 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.
Pathway DetailMolecule ListEnzyme ListReaction List