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Reaction Name | Pathway Name / Pathway No. | Kf | Kb | Kd | tau | Reagents |
1 | Ca5-bind-Cal | CaRegulation
Pathway No. 149 | 0.0005 (uM^-5 s^-1) | 1 (s^-1) | - | - | Substrate: Calseq Ca-sequester Ca-sequester Ca-sequester Ca-sequester Ca-sequester
Products: Ca5-Cal
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| There are actually 5 Ca-sequester substrates for this reaction, along with one Calseq. Due to system limitations only four are entered. | 2 | CaTraspATPase | CaRegulation
Pathway No. 149 | 25 (s^-1) | 0 (#^-2 s^-1) | Not applicable** | - | Substrate: CaTransp-2Ca
Products: CaTransp Ca-sequester Ca-sequester
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| kCa3 = 2 * Ca transporter rate since each step has 2 Ca++. = 0.5 uM/sec from Lauffenburger and Linderman 1993 Receptors pg200 The amount of the activated transporter is about 0.01 uM = 6e3#. from runs. So 0.01uM * kf * 2 = 0.5 uM/sec (no back reaction) so kf = 25, kb = 0 Alternatively, 6e3 * kf = 0.25 * 6e5, giving the same kf | 3 | Ca-bind-to-Trans p | CaRegulation
Pathway No. 149 | 3600 (uM^-2 s^-1) | 144 (s^-1) | Kd(af) = 0.2(uM) | - | Substrate: Ca Ca CaTransp
Products: CaTransp-2Ca
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| Rates from Lauffenburger abd Linderman 1993 Receptors pg 200. Kd = KCa2 = 0.2 uM | 4 | IP3Rbind | CaRegulation
Pathway No. 149 | 0.05 (uM^-3 s^-1) | 1 (s^-1) | Kd(af) = 2.7144(uM) | - | Substrate: IP3R IP3 IP3 IP3
Products: IP3R*
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| Based on Lauffenburger and Linderman 1993 Receptors pg 200. The binding of IP3 on this reaction had a Hill coeff of 3. The eqns of Mahama and Linderman (cited in the book as 1993 a) are equivalent to the binding all occurring in a single step, so that is how I do it in this version. Their Ki1 is 0.07 uM. Lots of other data sources: Ramos-Franco et al, Biophys J 75, 1998: 834-39 have Ca sensitivity curves. At 250 nM free Ca, the EC50 for type1 is 58 nM and type 2 is 194 nM. Type 3 would be about 2 uM according to Newton et al, JBC 268(46), 1994: 28613-19. For the purposes of this model we use a Kd of 2.7 uM which is high but maybe OK at low calcium. The details of Ca interaction with the IP3R are not included in this model. | 5 | inactivate_cap_ Ca | CaRegulation
Pathway No. 149 | 0 (#^-2 s^-1) | 1 (s^-1) | Not applicable** | - | Substrate: Ca-sequester Ca-sequester capacitive_Ca_ entry*
Products: inact_cap_entry
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| The Kd is set at about 3 uM so that at resting Ca the capacitative Ca entry is almost blocked. A 2nd order response makes the response steep. | 6 | Ca10-bind-Cal | CaRegulation
Pathway No. 149 | 0.0005 (uM^-5 s^-1) | 1 (s^-1) | - | - | Substrate: Ca5-Cal Ca-sequester Ca-sequester Ca-sequester Ca-sequester Ca-sequester
Products: Ca10-Cal
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| There are actually 5 Ca-sequester substrates for this reaction, along with Ca5-Cal. Due to system limitations only four are entered. | 7 | Ca15-bind-Cal | CaRegulation
Pathway No. 149 | 0.0005 (uM^-5 s^-1) | 1 (s^-1) | - | - | Substrate: Ca10-Cal Ca-sequester Ca-sequester Ca-sequester Ca-sequester Ca-sequester
Products: Ca15-Cal
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| There are actually 5 Ca-sequester substrates for this reaction, along with Ca10-Cal. Due to system limitations only four are entered. | 8 | Ca20-bind-Cal | CaRegulation
Pathway No. 149 | 0.0005 (uM^-5 s^-1) | 1 (s^-1) | - | - | Substrate: Ca15-Cal Ca-sequester Ca-sequester Ca-sequester Ca-sequester Ca-sequester
Products: Ca20-Cal
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| There are actually 5 Ca-sequester substrates for this reaction, along with Ca15-Cal. Due to system limitations only four are entered. | 9 | Ca25-bind-Cal | CaRegulation
Pathway No. 149 | 0.0005 (uM^-5 s^-1) | 1 (s^-1) | - | - | Substrate: Ca-sequester Ca-sequester Ca-sequester Ca-sequester Ca-sequester Ca20-Cal
Products: Ca25-Cal
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| There are actually 5 Ca-sequester substrates for this reaction, along with Ca20-Cal. Due to system limitations only four are entered. | 10 | Ca30-bind-Cal | CaRegulation
Pathway No. 149 | 0.0005 (uM^-5 s^-1) | 1 (s^-1) | - | - | Substrate: Ca25-Cal Ca-sequester Ca-sequester Ca-sequester Ca-sequester Ca-sequester
Products: Ca30-Cal
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| There are actually 5 Ca-sequester substrates for this reaction, along with Ca25-Cal. Due to system limitations only four are entered. | 11 | Ca35-bind-Cal | CaRegulation
Pathway No. 149 | 0.0005 (uM^-5 s^-1) | 1 (s^-1) | - | - | Substrate: Ca-sequester Ca-sequester Ca-sequester Ca-sequester Ca-sequester Ca30-Cal
Products: Ca35-Cal
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| There are actually 5 Ca-sequester substrates for this reaction, along with Ca30-Cal. Due to system limitations only four are entered. | 12 | Ca40-bind-Cal | CaRegulation
Pathway No. 149 | 0.0005 (uM^-5 s^-1) | 1 (s^-1) | - | - | Substrate: Ca-sequester Ca-sequester Ca-sequester Ca-sequester Ca-sequester Ca35-Cal
Products: Ca40-Cal
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| There are actually 5 Ca-sequester substrates for this reaction, along with Ca35-Cal. Due to system limitations only four are entered. |