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 Ras (Pathway Number 76)

 Molecule Name/
Site Name 		Km (uM) kcat (1/s)Ratio
(k2/k3)		Enzyme TypeSubstrate Product
1 Enzyme Activity:
CaM-GEF-act-ras

Enzyme Molecule:
CaM-GEF		0.50510.024explicit E-S complexGDP-Ras
GTP-Ras
  Kinetics same as GEF-bg_act-ras
2 Enzyme Activity:
GAP-inact-ras

Enzyme Molecule:
GAP		1.010410100explicit E-S complexGTP-Ras
GDP-Ras
  From Eccleston et al JBC 268(36)pp27012-19 get Kd < 2uM, kcat - 10/sec From Martin et al Cell 63 843-849 1990 get Kd ~ 250 nM, kcat = 20/min I will go with the Eccleston figures as there are good error bars (10%). The two sets of values are reasonably close. k1 = 1.666e-3/sec, k2 = 1000/sec, k3 = 10/sec (note k3 is rate-limiting) This is one of the rare cases where we have direct info on the k3 being rate-limiting. Hence the ratio I use for the k2:k3 rates is 100 rather than the usual 4.
3 Enzyme Activity:
GEF*-act-ras

Enzyme Molecule:
GEF*		0.50510.024explicit E-S complexGDP-Ras
GTP-Ras
  Kinetics from Orita et al JBC 268(34):25542-25546. Note that the Vmax is slow, but it does match the slow GTP hydrolysis rates.
4 Enzyme Activity:
GEF-bg_act-ras

Enzyme Molecule:
GEF-Gprot-bg		0.50510.024explicit E-S complexGDP-Ras
GTP-Ras
  Kinetics based on the activation of Gq by the receptor complex in the Gq model (in turn based on the Mahama and Linderman model) k1 = 2e-5, k2 = 1e-10, k3 = 10 (I do not know why they even bother with k2). Lets put k1 at 2e-6 to get a reasonable equilibrium More specific values from, eg.g: Orita et al JBC 268(34) 25542-25546 from rasGRF and smgGDS: k1=3.3e-7; k2 = 0.08, k3 = 0.02
Pathway DetailMolecule ListEnzyme ListReaction List