Imported:YPM/Dig1/Dig2/Ste12/MAPK binding rate constant constraints
Category:Yeast Pheromone Response Model
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Cooperative binding of Dig1 and Dig2 to Ste12
Kd_Ste12_Dig1
Ste12 + Kss1 + Dig1 + Dig2 <--------------------------> Ste12:Dig1 + Kss1 + Dig2
∧ ∧
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| Kd_Ste12_Dig2 | Kd_Ste12Dig1_Dig2
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∨ Kd_Ste12Dig2_Dig1 ∨
Ste12:Dig2 + Kss1 + Dig1 <----------------------------> Ste12:Dig1:Dig2 + Kss1
A quick analysis tells us that
Kd_Ste12_Dig1 * Kd_Ste12Dig1_Dig2 = Kd_Ste12_Dig2 * Kd_Ste12Dig2_Dig1
If we assume that kon_Ste12_Dig1 = kon_Ste12Dig2_Dig1, and kon_Ste12_Dig2 = kon_Ste12Dig1_Dig2 then we get
koff_Ste12_Dig1 / koff_Ste12Dig2_Dig1 = koff_Ste12_Dig2 / koff_Ste12Dig1_Dig2
which just states that the factor by which Dig2 changes Dig1's affinity for Ste12 is the same as the factor that Dig1 changes Dig2's affinity for Ste12. We can thus define a new parameter to help describe this relationship. Let Ste12_Dig1_Dig2_coop_factor be this cooperative factor. Thus
koff_Ste12Dig2_Dig1 = koff_Ste12_Dig1 / Ste12_Dig1_Dig2_coop_factor and koff_Ste12Dig1_Dig2 = koff_Ste12_Dig2 / Ste12_Dig1_Dig2_coop_factor
The independent parameters are:
and the dependent parameter are:
- kon_Ste12Dig2_Dig1 = kon_Ste12_Dig1
- kon_Ste12Dig1_Dig2 = kon_Ste12_Dig2
- koff_Ste12Dig2_Dig1 = koff_Ste12_Dig1 / Ste12_Dig1_Dig2_coop_factor
- koff_Ste12Dig1_Dig2 = koff_Ste12_Dig2 / Ste12_Dig1_Dig2_coop_factor
Effect of Dig1 and Dig2 phosphorylation on their binding to Ste12
Dig1 phosphorylation
Kd_Ste12_Dig1PO4
Ste12 + Kss1 + Dig1PO4 + Dig2 <------------------------> Ste12:Dig1PO4 + Kss1 + Dig2
∧ ∧
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| Kd_Ste12_Dig2 | Kd_Ste12Dig1_Dig2
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∨ Kd_Ste12Dig2_Dig1PO4 ∨
Ste12:Dig2 + Kss1 + Dig1PO4 <--------------------------> Ste12:Dig1PO4:Dig2 + Kss1
A quick analysis tells us that
Kd_Ste12_Dig1PO4 * Kd_Ste12Dig1_Dig2 = Kd_Ste12_Dig2 * Kd_Ste12Dig2_Dig1PO4
If we assume that kon_Ste12_Dig1PO4 = kon_Ste12Dig2_Dig1PO4 = kon_Ste12_Dig1, then
koff_Ste12_Dig1PO4 / koff_Ste12Dig2_Dig1PO4 = koff_Ste12_Dig2 / koff_Ste12Dig1_Dig2 = Ste12_Dig1_Dig2_coop_factor
Now, taking into account the effect of Dig1 phosphorylation, we can define Kd_Ste12_Dig1PO4 = Ste12_Dig1_PO4_factor * Kd_Ste12_Dig1, so
koff_Ste12_Dig1PO4 = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 and koff_Ste12Dig2_Dig1PO4 = koff_Ste12_Dig1PO4 / Ste12_Dig1_Dig2_coop_factor = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 / Ste12_Dig1_Dig2_coop_factor
The independent parameters are:
and the dependent parameters are:
- kon_Ste12_Dig1PO4 = kon_Ste12_Dig1
- kon_Ste12Dig2_Dig1PO4 = kon_Ste12_Dig1
- koff_Ste12_Dig1PO4 = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1
- koff_Ste12Dig2_Dig1PO4 = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 / Ste12_Dig1_Dig2_coop_factor
Dig2 phosphorylation
Kd_Ste12_Dig1
Ste12 + Kss1 + Dig1 + Dig2PO4 <--------------------------> Ste12:Dig1 + Kss1 + Dig2
∧ ∧
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| Kd_Ste12_Dig2PO4 | Kd_Ste12Dig1_Dig2PO4
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∨ Kd_Ste12Dig2_Dig1 ∨
Ste12:Dig2 + Kss1 + Dig1 <----------------------------> Ste12:Dig1:Dig2 + Kss1
A quick analysis tells us that
Kd_Ste12_Dig1 * Kd_Ste12Dig1_Dig2PO4 = Kd_Ste12_Dig2PO4 * Kd_Ste12Dig2_Dig1
If we assume that kon_Ste12_Dig2PO4 = kon_Ste12Dig1_Dig2PO4 = kon_Ste12_Dig2, then
koff_Ste12_Dig2PO4 / koff_Ste12Dig1_Dig2PO4 = koff_Ste12_Dig1 / koff_Ste12Dig2_Dig1 = Ste12_Dig1_Dig2_coop_factor
Now, taking into account the effect of Dig2 phosphorylation, we can define Kd_Ste12_Dig2PO4 = Ste12_Dig2_PO4_factor * Kd_Ste12_Dig1, so
koff_Ste12_Dig2PO4 = Ste12_Dig2_PO4_factor * koff_Ste12_Dig2 and koff_Ste12Dig1_Dig2PO4 = koff_Ste12_Dig2PO4 / Ste12_Dig1_Dig2_coop_factor = Ste12_Dig2_PO4_factor * koff_Ste12_Dig2 / Ste12_Dig1_Dig2_coop_factor
The independent parameters are:
and the dependent parameters are:
- kon_Ste12_Dig2PO4 = kon_Ste12_Dig2
- kon_Ste12Dig1_Dig2PO4 = kon_Ste12_Dig2
- koff_Ste12_Dig2PO4 = Ste12_Dig2_PO4_factor * koff_Ste12_Dig2
- koff_Ste12Dig1_Dig2PO4 = Ste12_Dig2_PO4_factor * koff_Ste12_Dig2 / Ste12_Dig1_Dig2_coop_factor
Cooperative binding of Kss1 and Dig1 to Ste12
Dig2 absent and Dig1 unphosphorylated
Kd_Ste12_Dig1
Ste12 + Kss1 + Dig1 + Dig2 <--------------------------> Ste12:Dig1 + Kss1 + Dig2
∧ ∧
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| Kd_Ste12_Kss1 | Kd_Ste12Dig1_Kss1
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∨ Kd_Ste12Kss1_Dig1 ∨
Ste12:Kss1 + Dig1 + Dig2 <----------------------------> Ste12:Kss1:Dig1 + Dig2
A quick analysis tells us that
Kd_Ste12_Dig1 * Kd_Ste12Dig1_Kss1 = Kd_Ste12_Kss1 * Kd_Ste12Kss1_Dig1
If we assume that kon_Ste12_Dig1 = kon_Ste12Kss1_Dig1 and kon_Ste12_Kss1 = kon_Ste12Dig1_Kss1 then we get
koff_Ste12_Dig1 / koff_Ste12Kss1_Dig1 = koff_Ste12_Kss1 / koff_Ste12Dig1_Kss1
which just states that the factor by which Kss1 changes Dig1's affinity for Ste12 is the same as the factor that Dig1 changes Kss1's affinity for Ste12. We can thus define a new parameter to help describe this relationship. Let Ste12_Dig1_Kss1_coop_factor be this cooperative factor. Thus
koff_Ste12Kss1_Dig1 = koff_Ste12_Dig1 / Ste12_Dig1_Kss1_coop_factor and koff_Ste12Dig1_Kss1 = koff_Ste12_Kss1 / Ste12_Dig1_Kss1_coop_factor
The independent parameters are:
and the dependent parameters are:
- kon_Ste12Kss1_Dig1 = kon_Ste12_Dig1
- kon_Ste12Dig1_Kss1 = kon_Ste12_Kss1
- koff_Ste12Kss1_Dig1 = koff_Ste12_Dig1 / Ste12_Dig1_Kss1_coop_factor
- koff_Ste12Dig1_Kss1 = koff_Ste12_Kss1 / Ste12_Dig1_Kss1_coop_factor
Dig2 present and Dig1 unphosphorylated
Kd_Ste12Dig2_Dig1
Ste12:Dig2 + Kss1 + Dig1 <----------------------------> Ste12:Dig1:Dig2 + Kss1
∧ ∧
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| Kd_Ste12_Kss1 | Kd_Ste12Dig1_Kss1
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∨ Kd_Ste12Kss1Dig2_Dig1 ∨
Ste12:Kss1:Dig2 + Dig1 <------------------------------> Ste12:Kss1:Dig1:Dig2
A quick analysis tells us that
Kd_Ste12Dig2_Dig1 * Kd_Ste12Dig1_Kss1 = Kd_Ste12_Kss1 * Kd_Ste12Kss1Dig2_Dig1
If we assume that kon_Ste12Kss1Dig2_Dig1 = kon_Ste12Dig2_Dig1 (= kon_Ste12_Dig1) then we get
koff_Ste12Dig2_Dig1 / koff_Ste12Kss1Dig2_Dig1 = koff_Ste12_Kss1 / koff_Ste12Dig1_Kss1 = Ste12_Dig1_Kss1_coop_factor
so
koff_Ste12Kss1Dig2_Dig1 = koff_Ste12Dig2_Dig1 / Ste12_Dig1_Kss1_coop_factor = koff_Ste12_Dig1 / (Ste12_Dig1_Dig2_coop_factor * Ste12_Dig1_Kss1_coop_factor)
There are no independent parameters are, and the dependent parameters are:
- kon_Ste12Kss1Dig2_Dig1 = kon_Ste12_Dig1
- koff_Ste12Kss1Dig2_Dig1 = koff_Ste12_Dig1 / (Ste12_Dig1_Dig2_coop_factor * Ste12_Dig1_Kss1_coop_factor)
Dig2 absent and Dig1 phosphorylated
Kd_Ste12_Dig1PO4
Ste12 + Kss1 + Dig1PO4 + Dig2 <------------------------> Ste12:Dig1PO4 + Kss1 + Dig2
∧ ∧
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| Kd_Ste12_Kss1 | Kd_Ste12Dig1_Kss1
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∨ Kd_Ste12Kss1_Dig1PO4 ∨
Ste12:Kss1 + Dig1PO4 + Dig2 <--------------------------> Ste12:Kss1:Dig1PO4 + Dig2
A quick analysis tells us that
Kd_Ste12_Dig1PO4 * Kd_Ste12Dig1_Kss1 = Kd_Ste12_Kss1 * Kd_Ste12Kss1_Dig1PO4
If we assume that kon_Ste12Kss1_Dig1PO4 = kon_Ste12_Dig1PO4 (= kon_Ste12_Dig1) then we get
koff_Ste12_Dig1PO4 / koff_Ste12Kss1_Dig1PO4 = koff_Ste12_Kss1 / koff_Ste12Dig1_Kss1 = Ste12_Dig1_Kss1_coop_factor
so
koff_Ste12Kss1_Dig1PO4 = koff_Ste12_Dig1PO4 / Ste12_Dig1_Kss1_coop_factor = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 / Ste12_Dig1_Kss1_coop_factor
There are no independent parameters, and the dependent parameters are:
- kon_Ste12Kss1_Dig1PO4 = kon_Ste12_Dig1
- koff_Ste12Kss1_Dig1PO4 = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 / Ste12_Dig1_Kss1_coop_factor
Dig2 present and Dig1 phosphorylated
First examine the effect of Dig2 and Dig1 phosphorylation in the absence of Kss1:
Kd_Ste12Dig2_Dig1PO4
Ste12:Dig2 + Kss1 + Dig1PO4 <-------------------------> Ste12:Dig1PO4:Dig2 + Kss1 + Dig2
∧ ∧
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| Kd_Ste12_Kss1 | Kd_Ste12Dig1_Kss1
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∨ Kd_Ste12Kss1Dig2_Dig1PO4 ∨
Ste12:Kss1:Dig2 + Dig1PO4 <--------------------------> Ste12:Kss1:Dig1PO4:Dig2
A quick analysis tells us that
Kd_Ste12Dig2_Dig1PO4 * Kd_Ste12Dig1_Kss1 = Kd_Ste12_Kss1 * Kd_Ste12Kss1Dig2_Dig1PO4
If we assume that kon_Ste12Kss1Dig2_Dig1PO4 = kon_Ste12Dig2_Dig1PO4 (= kon_Ste12_Dig1) then we get
koff_Ste12Dig2_Dig1PO4 / koff_Ste12Kss1Dig2_Dig1PO4 = koff_Ste12_Kss1 / koff_Ste12Dig1_Kss1 = Ste12_Dig1_Kss1_coop_factor
so
koff_Ste12Kss1Dig2_Dig1PO4 = koff_Ste12Dig2_Dig1PO4 / Ste12_Dig1_Kss1_coop_factor = koff_Ste12_Dig1PO4 / (Ste12_Dig1_Dig2_coop_factor * Ste12_Dig1_Kss1_coop_factor) = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 / (Ste12_Dig1_Dig2_coop_factor * Ste12_Dig1_Kss1_coop_factor)
There are no independent parameters, and the dependent parameters are:
- kon_Ste12Kss1Dig2_Dig1PO4 = kon_Ste12_Dig1
- koff_Ste12Kss1Dig2_Dig1PO4 = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 / (Ste12_Dig1_Dig2_coop_factor * Ste12_Dig1_Kss1_coop_factor)
Effect of Kss1 phosphorylation on its association with Ste12
Kss1pT
Kd_Ste12_Kss1pT
Ste12 + Kss1pT + Dig1 + Dig2 <------------------------> Ste12:Kss1pT + Dig1 + Dig2
∧ ∧
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| Kd_Ste12_Dig1 | Kd_Ste12Kss1_Dig1
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∨ Kd_Ste12Dig1_Kss1pT ∨
Ste12:Dig1 + Kss1pT + Dig2 <--------------------------> Ste12:Kss1pT:Dig1 + Dig2
A quick analysis tells us that
Kd_Ste12_Kss1pT * Kd_Ste12Kss1_Dig1 = Kd_Ste12_Dig1 * Kd_Ste12Dig1_Kss1pT
If we assume that kon_Ste12_Kss1pT = kon_Ste12Dig1_Kss1pT = kon_Ste12_Kss1, then
koff_Ste12_Kss1pT / koff_Ste12Dig1_Kss1pT = koff_Ste12_Dig1 / koff_Ste12Kss1_Dig1 = Ste12_Dig1_Kss1_coop_factor
Now also define Ste12_Kss1_pT_factor such that koff_Ste12_Kss1pT / koff_Ste12_Kss1 = Ste12_Kss1_pT_factor. Therefore
koff_Ste12_Kss1pT = Ste12_Kss1_pT_factor * koff_Ste12_Kss1 and koff_Ste12Dig1_Kss1pT = koff_Ste12_Kss1pT / Ste12_Dig1_Kss1_coop_factor = Ste12_Kss1_pT_factor * koff_Ste12_Kss1 / Ste12_Dig1_Kss1_coop_factor
The independent parameters are:
and the dependent parameters are:
- kon_Ste12_Kss1pT = kon_Ste12_Kss1
- kon_Ste12Dig1_Kss1pT = kon_Ste12_Kss1
- koff_Ste12_Kss1pT = Ste12_Kss1_pT_factor * koff_Ste12_Kss1
- koff_Ste12Dig1_Kss1pT = Ste12_Kss1_pT_factor * koff_Ste12_Kss1 / Ste12_Dig1_Kss1_coop_factor
Kss1pY
We can perform an identical procedure to that performed for Kss1pT in order to get the binding parameters for Kss1pY.
The independent parameters are:
and the dependent parameters are:
- kon_Ste12_Kss1pY = kon_Ste12_Kss1
- kon_Ste12Dig1_Kss1pY = kon_Ste12_Kss1
- koff_Ste12_Kss1pY = Ste12_Kss1_pY_factor * koff_Ste12_Kss1
- koff_Ste12Dig1_Kss1pY = Ste12_Kss1_pY_factor * koff_Ste12_Kss1 / Ste12_Dig1_Kss1_coop_factor
Kss1pTpY
We can perform an identical procedure to that performed for Kss1pT in order to get the binding parameters for Kss1pTpY.
The independent parameters are:
and the dependent parameters are:
- kon_Ste12_Kss1pTpY = kon_Ste12_Kss1
- kon_Ste12Dig1_Kss1pTpY = kon_Ste12_Kss1
- koff_Ste12_Kss1pTpY = Ste12_Kss1_pTpY_factor * koff_Ste12_Kss1
- koff_Ste12Dig1_Kss1pTpY = Ste12_Kss1_pTpY_factor * koff_Ste12_Kss1 / Ste12_Dig1_Kss1_coop_factor
Fus3 vs Kss1 involvement
Analogous reasoning can be used to determine the involvement of Fus3 in the above interactions. The parameters involving Fus3 are listed in the summary below.
Summary of Parameters
Cooperative factors:
Ste12_Dig1_PO4_factor Ste12_Dig2_PO4_factor Ste12_Dig1_Dig2_coop_factor Ste12_Dig1_Kss1_coop_factor Ste12_Dig1_Fus3_coop_factor Ste12_Kss1_pT_factor Ste12_Kss1_pY_factor Ste12_Kss1_pTpY_factor Ste12_Fus3_pT_factor Ste12_Fus3_pY_factor Ste12_Fus3_pTpY_factor
Ste12/Dig1 association:
kon_Ste12_Dig1 kon_Ste12_Dig1PO4 = kon_Ste12_Dig1 kon_Ste12Dig2_Dig1 = kon_Ste12_Dig1 kon_Ste12Dig2_Dig1PO4 = kon_Ste12_Dig1 kon_Ste12Kss1_Dig1 = kon_Ste12_Dig1 kon_Ste12Kss1_Dig1PO4 = kon_Ste12_Dig1 kon_Ste12Kss1Dig2_Dig1 = kon_Ste12_Dig1 kon_Ste12Kss1Dig2_Dig1PO4 = kon_Ste12_Dig1 kon_Ste12Fus3_Dig1 = kon_Ste12_Dig1 kon_Ste12Fus3_Dig1PO4 = kon_Ste12_Dig1 kon_Ste12Fus3Dig2_Dig1 = kon_Ste12_Dig1 kon_Ste12Fus3Dig2_Dig1PO4 = kon_Ste12_Dig1 koff_Ste12_Dig1 koff_Ste12_Dig1PO4 = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 koff_Ste12Dig2_Dig1 = koff_Ste12_Dig1 / Ste12_Dig1_Dig2_coop_factor koff_Ste12Dig2_Dig1PO4 = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 / Ste12_Dig1_Dig2_coop_factor koff_Ste12Kss1_Dig1 = koff_Ste12_Dig1 / Ste12_Dig1_Kss1_coop_factor koff_Ste12Kss1_Dig1PO4 = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 / Ste12_Dig1_Kss1_coop_factor koff_Ste12Kss1Dig2_Dig1 = koff_Ste12_Dig1 / (Ste12_Dig1_Dig2_coop_factor * Ste12_Dig1_Kss1_coop_factor) koff_Ste12Kss1Dig2_Dig1PO4 = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 / (Ste12_Dig1_Dig2_coop_factor * Ste12_Dig1_Kss1_coop_factor) koff_Ste12Fus3_Dig1 = koff_Ste12_Dig1 / Ste12_Dig1_Fus3_coop_factor koff_Ste12Fus3_Dig1PO4 = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 / Ste12_Dig1_Fus3_coop_factor koff_Ste12Fus3Dig2_Dig1 = koff_Ste12_Dig1 / (Ste12_Dig1_Dig2_coop_factor * Ste12_Dig1_Fus3_coop_factor) koff_Ste12Fus3Dig2_Dig1PO4 = Ste12_Dig1_PO4_factor * koff_Ste12_Dig1 / (Ste12_Dig1_Dig2_coop_factor * Ste12_Dig1_Fus3_coop_factor)
Ste12/Dig2 association:
kon_Ste12_Dig2 kon_Ste12_Dig2PO4 = kon_Ste12_Dig2 kon_Ste12Dig1_Dig2 = kon_Ste12_Dig2 kon_Ste12Dig1_Dig2PO4 = kon_Ste12_Dig2 koff_Ste12_Dig2 koff_Ste12_Dig2PO4 = Ste12_Dig2_PO4_factor * koff_Ste12_Dig2 koff_Ste12Dig1_Dig2 = koff_Ste12_Dig2 / Ste12_Dig1_Dig2_coop_factor koff_Ste12Dig1_Dig2PO4 = Ste12_Dig2_PO4_factor * koff_Ste12_Dig2 / Ste12_Dig1_Dig2_coop_factor
Ste12_Kss1 association:
kon_Ste12_Kss1 kon_Ste12_Kss1pT = kon_Ste12_Kss1 kon_Ste12_Kss1pY = kon_Ste12_Kss1 kon_Ste12_Kss1pTpY = kon_Ste12_Kss1 kon_Ste12Dig1_Kss1 = kon_Ste12_Kss1 kon_Ste12Dig1_Kss1pT = kon_Ste12_Kss1 kon_Ste12Dig1_Kss1pY = kon_Ste12_Kss1 kon_Ste12Dig1_Kss1pTpY = kon_Ste12_Kss1 koff_Ste12_Kss1 koff_Ste12_Kss1pT = Ste12_Kss1_pT_factor * koff_Ste12_Kss1 koff_Ste12_Kss1pY = Ste12_Kss1_pY_factor * koff_Ste12_Kss1 koff_Ste12_Kss1pTpY = Ste12_Kss1_pTpY_factor * koff_Ste12_Kss1 koff_Ste12Dig1_Kss1 = koff_Ste12_Kss1 / Ste12_Dig1_Kss1_coop_factor koff_Ste12Dig1_Kss1pT = Ste12_Kss1_pT_factor * koff_Ste12_Kss1 / Ste12_Dig1_Kss1_coop_factor koff_Ste12Dig1_Kss1pY = Ste12_Kss1_pY_factor * koff_Ste12_Kss1 / Ste12_Dig1_Kss1_coop_factor koff_Ste12Dig1_Kss1pTpY = Ste12_Kss1_pTpY_factor * koff_Ste12_Kss1 / Ste12_Dig1_Kss1_coop_factor
Ste12_Fus3 association:
kon_Ste12_Fus3 kon_Ste12_Fus3pT = kon_Ste12_Fus3 kon_Ste12_Fus3pY = kon_Ste12_Fus3 kon_Ste12_Fus3pTpY = kon_Ste12_Fus3 kon_Ste12Dig1_Fus3 = kon_Ste12_Fus3 kon_Ste12Dig1_Fus3pT = kon_Ste12_Fus3 kon_Ste12Dig1_Fus3pY = kon_Ste12_Fus3 kon_Ste12Dig1_Fus3pTpY = kon_Ste12_Fus3 koff_Ste12_Fus3 koff_Ste12_Fus3pT = Ste12_Fus3_pT_factor * koff_Ste12_Fus3 koff_Ste12_Fus3pY = Ste12_Fus3_pY_factor * koff_Ste12_Fus3 koff_Ste12_Fus3pTpY = Ste12_Fus3_pTpY_factor * koff_Ste12_Fus3 koff_Ste12Dig1_Fus3 = koff_Ste12_Fus3 / Ste12_Dig1_Fus3_coop_factor koff_Ste12Dig1_Fus3pT = Ste12_Fus3_pT_factor * koff_Ste12_Fus3 / Ste12_Dig1_Fus3_coop_factor koff_Ste12Dig1_Fus3pY = Ste12_Fus3_pY_factor * koff_Ste12_Fus3 / Ste12_Dig1_Fus3_coop_factor koff_Ste12Dig1_Fus3pTpY = Ste12_Fus3_pTpY_factor * koff_Ste12_Fus3 / Ste12_Dig1_Fus3_coop_factor
