| |
Reaction
Name | Pathway Name /
Pathway No. | Kf | Kb | Kd | tau | Reagents |
| 1 | IP5-inhib-3pase | 1345_dephos
Pathway No. 156 | 1
(uM^-1 s^-1) | 0.06
(s^-1) | Kd(bf) = 0.06(uM) | - | Substrate:
1345_3pase
IP5(13456)
Products:
IP5-3pase-cmplx
|
| from Hoer and Oberdisse, Biochem J 278; 1991: 219-224 | | 2 | IP6-inhib-3pase | 1345_dephos
Pathway No. 156 | 1
(uM^-1 s^-1) | 0.003
(s^-1) | Kd(bf) = 0.003(uM) | - | Substrate:
1345_3pase
IP6
Products:
IP6-inhib-3pase-
cmplx
|
| from Hoer and Oberdisse, Biochem J 278; 1991: 219-224 | | 3 | 145-inhib-3pase | 1345_dephos
Pathway No. 156 | 1
(uM^-1 s^-1) | 1.75
(s^-1) | Kd(bf) = 1.75(uM) | - | Substrate:
1345_3pase
IP3(145)
Products:
IP3(145)-3pase-c
mplx
|
| from Hoer et al, Biochem J 270; 1990 | | 4 | IP4-inhib-3pase | 1345_dephos
Pathway No. 156 | 1
(uM^-1 s^-1) | 0.5
(s^-1) | Kd(bf) = 0.5(uM) | - | Substrate:
IP4(3456)
1345_3pase
Products:
IP4-3pase-cmplx
|
| from Hoer et al, Biochem J 270; 1990 | | 5 | 134-inhib-3pase | 1345_dephos
Pathway No. 156 | 1
(uM^-1 s^-1) | 2
(s^-1) | Kd(bf) = 2(uM) | - | Substrate:
1345_3pase
IP3(134)
Products:
IP3(134)-3pase-c
mplx
|
| from Hoer et al, Biochem J 270; 1990 | | 6 | dipp_ip6 | IHP-system
Pathway No. 155 | 0
(s^-1) | 0
(s^-1) | - | - | Substrate:
PP-IP4
Products:
IP5(13456)
|
| rate based on basal levels of PP-InsP4 | | 7 | ip5-kinase-pase | IHP-system
Pathway No. 155 | 1
(s^-1) | 1.92
(s^-1) | Keq = 1.92(uM) | 0.342sec | Substrate:
IP5(13456)
Products:
IP6
|
| Kf represents InsP5 2-kinase and Kb represents InsP6 2-phosphatase Although InsP5 2-kinases in yeast and plant systems have been characterized (Ives et al, JBC 275; 2000: 36575-83), the mammalian counterpart is still to be worked out. Rates calculated to maintain InsP5 and InsP6 levels | | 8 | IP5-dipp-inhib | IHP-system
Pathway No. 155 | 1
(uM^-1 s^-1) | 1.6
(s^-1) | Kd(bf) = 1.6(uM) | - | Substrate:
DIPP1
IP5(13456)
Products:
IP5-DIPPcmplx
|
| IC50=1.6uM from Safrany et al, EMBO J 17(22); 1998 | | 9 | IP6-dipp-inhib | IHP-system
Pathway No. 155 | 1
(uM^-1 s^-1) | 0.2
(s^-1) | Kd(bf) = 0.2(uM) | - | Substrate:
IP6
DIPP1
Products:
IP6-DIPPcmplx
|
| IC50=0.2uM from Safrany et al, EMBO J 17(22); 1998 | | 10 | PP-IP5cmplx-on | IHP-system
Pathway No. 155 | 0.0027
(uM^-2 s^-1) | 2.5
(s^-1) | - | - | Substrate:
ATP
PP-IP5
PP-IP5-K
Products:
PP-IP5-K-complex
|
| from Huang et al, Biochem 37; 1998 Kf calculated using Km for PP-InsP5 and ATP, and Vmax of forward and backward reactions. Kb = Vmax of backward reaction | | 11 | PP-IP5cmplx-off | IHP-system
Pathway No. 155 | 1
(s^-1) | 0.0013
(uM^-2 s^-1) | - | - | Substrate:
PP-IP5-K-complex
Products:
ADP
bisPP-IP4
PP-IP5-K
|
| from Huang et al, Biochem 37; 1998 Kf = Vmax of forward reaction Kb calculated using Km for PP-InsP5 and ATP, and Vmax of forward and backward reactions | | 12 | IP6cmplx-off | IHP-system
Pathway No. 155 | 1.26
(s^-1) | 0.0012
(uM^-2 s^-1) | - | - | Substrate:
IP6-K-complex
Products:
PP-IP5
ADP
IP6-K
|
| from Voglmaier et al, PNAS 93; 1996 Kf = Vmax of forward reaction Kb calculated from Km for InsP6 and ATP, and Vmax of forward and backward reactions | | 13 | IP6cmplx-on | IHP-system
Pathway No. 155 | 0.0038
(uM^-2 s^-1) | 2.376
(s^-1) | - | - | Substrate:
IP6
ATP
IP6-K
Products:
IP6-K-complex
|
| from Voglmaier et al, PNAS 93; 1996 Kf calculated from Km for InsP6 and ATP, and Vmax for forward and backward reactions Kb = Vmax of backward reaction | | 14 | ip4-6pase | IP4-system
Pathway No. 154 | 0.013
(s^-1) | 0
(s^-1) | - | - | Substrate:
IP4(1456)
Products:
IP3(145)
|
| this step is essential to maintain flux around the network, rate adjusted accordingly | | 15 | ip5_3pase | IP4-system
Pathway No. 154 | 0.0003
(s^-1) | 0
(s^-1) | - | - | Substrate:
IP5(13456)
Products:
IP4(1456)
|
| Ins(13456)P5 3-phosphatase from Nogimori et al, JBC 266; 1991 Backflux from the reversible InsP4 3-kinase is not sufficient to maintain Ins(1456)P4 levels. Hence this reaction is necessary. This reaction also maintains the flux in the network. | | 16 | IP3-Kcmplx-on | IP4-system
Pathway No. 154 | 4.2666
(uM^-1 s^-1) | 1.024
(s^-1) | Kd(bf) = 0.24(uM) | - | Substrate:
IP3(134)
IP3-56K_IP4-1K
Products:
IP3-56Kcmplx
|
| Kf and Kb are equivalent to k1 and k2 for InsP3 56-K, calculated from enzyme Km and Vmax: Yang and Shears, BiochemJ 2000, 351: 551-555 | | 17 | 6kinase | IP4-system
Pathway No. 154 | 0.256
(s^-1) | 0
(uM^-1 s^-1) | - | - | Substrate:
IP3-56Kcmplx
Products:
IP4(1346)
IP3-56K_IP4-1K
|
| Kf = Vmax for IP3 56-K from Yang and Shears, Biochem J 2000; 351:551-555 Enzyme reversibility reported in Ho et al, Curr Biol 2002, 12: 1-20. But backflow calculations do not show that Kb needs to be incorporated | | 18 | 5kinase | IP4-system
Pathway No. 154 | 0.0701
(s^-1) | 0.006
(uM^-1 s^-1) | Kd(cb) = 0.086(uM) | - | Substrate:
IP3-56Kcmplx
Products:
IP4(1345)
IP3-56K_IP4-1K
|
| Kf = 0.274 times Vmax of IP3 56-K as product ratio of Ins(1345)P4 : Ins(1346)P4 is 1 : 2.3-5 from Wilson and Majerus, JBC 271; 1996 Kb ascertained from dG calculations for equilibrium conditions., for a dG = -10 kJ/mol Also enzyme reversibility reported in Ho et al, Curr Biol 2002, 12: 1-20 | | 19 | ip4-5K | IP4-system
Pathway No. 154 | 0.15
(s^-1) | 0.003
(s^-1) | Keq = 0.02(uM) | 6.536sec | Substrate:
IP4(1346)
Products:
IP5(13456)
|
| Kf based on basal levels of Ins(1346)P4 Kb obtained from dG calculations for equilibrium product substrate conditions. | | 20 | ip4-3k-on | IP4-system
Pathway No. 154 | 53.7501
(uM^-1 s^-1) | 17.2
(s^-1) | Kd(bf) = 0.32(uM) | - | Substrate:
IP4(1456)
IP4-3K
Products:
ip4_3k_cmplx
|
| Rates derived from Km for enzyme: Stephens et al, Biochem J 249; 1988. |
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