| | Molecule Name/
Site Name | Km (uM) | kcat (1/s) | Ratio
(k2/k3) | Enzyme Type | Substrate | Product |
| 1 |
Enzyme Activity:
craf**-deph
Enzyme Molecule:
PPhosphatase2A | 15.6566 | 6 | 4.16667 | explicit E-S complex | craf-1**
| craf-1*
|
| | Ueki et al JBC 269(22) pp 15756-15761 1994 show hyperphosphorylation of craf, so this is there to dephosphorylate it. Identity of phosphatase is assumed to be PP2A. |
| 2 |
Enzyme Activity:
craf-deph
Enzyme Molecule:
PPhosphatase2A | 15.6566 | 6 | 4.16667 | explicit E-S complex | craf-1*
| craf-1
|
| | See parent PPhosphatase2A for parms |
| 3 |
Enzyme Activity:
MAPK*
Enzyme Molecule:
MAPK* | 25.641 | 20 | 4 | explicit E-S complex | PLA2-cytosolic
| PLA2*
|
| | Km = 25uM @ 50 uM ATP and 1mg/ml MBP (huge XS of substrate) Vmax = 4124 pmol/min/ml at a conc of 125 pmol/ml of enz. Numbers are from Sanghera et al JBC 265 pp 52 , 1990. From Nemenoff et al 1993 JBC 268(3):1960-1964 - using Sanghera's 1e-4 ratio of MAPK to protein, we get k3 = 7/sec from 1000 pmol/min/mg total protein in fig 5 I take the Vmax to be higher for PLA2 given the fold activation of PLA2 by MAPK. This is actually a balance term between MAPK and the dephosphorylation step. |
| 4 |
Enzyme Activity:
MAPK*-feedback
Enzyme Molecule:
MAPK* | 25.641 | 10 | 4 | explicit E-S complex | craf-1*
| craf-1**
|
| | Ueki et al JBC 269(22):15756-15761 show the presence of this step, but not the rate consts, which are derived from Sanghera et al JBC 265(1):52-57, 1990, see the deriv in the MAPK* notes. |
| 5 |
Enzyme Activity:
MAPKK-deph
Enzyme Molecule:
PPhosphatase2A | 15.6566 | 6 | 4.16667 | explicit E-S complex | MAPKK*
| MAPKK-ser
|
| | See: Kyriakis et al Nature 358 pp 417-421 1992 Ahn et al Curr Op Cell Biol 4:992-999 1992 for this pathway. See parent PPhosphatase2A for parms. |
| 6 |
Enzyme Activity:
MAPKK-deph-ser
Enzyme Molecule:
PPhosphatase2A | 15.6566 | 6 | 4.16667 | explicit E-S complex | MAPKK-ser
| MAPKK
|
| | See parent PPhostphatase2A description for rate details |
| 7 |
Enzyme Activity:
MKP2-thr-deph
Enzyme Molecule:
MKP-2 | 0.0666667 | 1 | 4 | explicit E-S complex | MAPK*
| MAPK-tyr
|
| | See MKP2-tyr-deph |
| 8 |
Enzyme Activity:
MKP2-tyr-deph
Enzyme Molecule:
MKP-2 | 0.0666667 | 1 | 4 | explicit E-S complex | MAPK-tyr
| MAPK
|
| | 22 Apr 2001: Based on MKP1 parms. The original kinetics have been modified to obey the k2 = 4 * k3 rule, while keeping kcat and Km fixed. The only constraining data point is the time course of MAPK dephosphorylation, which this model satisfies. The rates are treated as the same as for MKP-1, based on Chu et al 1995 JBC 271(11):6497-6501 |
| 9 |
Enzyme Activity:
PKC-act-GEF
Enzyme Molecule:
PKC-active | 66.6667 | 4 | 4 | explicit E-S complex | inact-GEF
| GEF*
|
| | Rate constants are generic PKC rates. See Chen et al 1993 Biochem 32:1032 This reaction activates GEF. Gives >= 2X stim of ras, and a 2X stim of MAPK over amount from direct phosph of c-raf. Note that it is a push-pull reaction, and also get effect through phosph and inact of GAPs. |
| 10 |
Enzyme Activity:
PKC-act-raf
Enzyme Molecule:
PKC-active | 66.6667 | 4 | 4 | explicit E-S complex | craf-1
| craf-1*
|
| | Rate consts from Chen et al Biochem 32, 1032 (1993) k3 = 4 Km for this substrate is trickier. Specific substrates are in the uM range, so we use a higher Km here. This may be too conservative in which case PKC would have a still higher effect on raf. The presence of this phosphorylation and activation step is from Kolch et al 1993 Nature 364:249 |
| 11 |
Enzyme Activity:
PKC-inact-GAP
Enzyme Molecule:
PKC-active | 66.6667 | 25 | 4 | explicit E-S complex | GAP
| GAP*
|
| | Rate consts are PKC generic rates. This reaction inactivates GAP. The reaction is from the Boguski and McCormick 1993 review in Nature 366:643-654 The phosphorylation Vmax is 6x higher to account for balance of GDP-Ras:GDP-Ras. |
| 12 |
Enzyme Activity:
Sos.Ras_GEF
Enzyme Molecule:
Shc*.Sos.Grb2 | 0.505051 | 0.02 | 4 | explicit E-S complex | GDP-Ras
| GTP-Ras
|
| | Rates from Orita et al JBC 268(34):25542-25546 |
