<ReactionScheme>
<Specie name="gaba" id="gaba" kdiff="111.4" kdiffunit="mu2/s"/>
<Specie name="gabaOut" id="gabaOut" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="GABABR" id="GABABR" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="gabaGABABR" id="gabaGABABR" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="Gi" id="Gi" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="GABABRGi" id="GABABRGi" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="gabaGABABRGi" id="gabaGABABRGi" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="gabaGABABRGibg" id="gabaGABABRGibg" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="GiaGTP" id="GiaGTP" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="GiaGDP" id="GiaGDP" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="RGS" id="RGS" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="GiaGTPRGS" id="GiaGTPRGS" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="Gibg" id="Gibg" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="GIRK" id="GIRK" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="VGCC" id="VGCC" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="GIRKGibg" id="GIRKGibg" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="GIRKGibg2" id="GIRKGibg2" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="GIRKGibg3" id="GIRKGibg3" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="GIRKGibg4" id="GIRKGibg4" kdiff="0" kdiffunit="mu2/s"/>
<Specie name="VGCCGibg" id="VGCCGibg" kdiff="0" kdiffunit="mu2/s"/>
<!--Tuomo: GABA leak out of the area near the membrane to the rest of the extracellular medium copied from the corresponding reaction Glu->GluOut in Maki-Marttunen et al. 2020-->
<!--Tuomo: Binding of gaba to GABABR copied from the reactions between L and R in Jedrzejewska-Sczmek et al. 2017-->
<!--Tuomo: Activation of Gi protein copied from the reactions between quatro-phosphorylated receptor and Gi in Jedrzejewska-Sczmek et al. 2017-->
<Reaction name = "gaba--gabaOut" id="gaba--gabaOut">
<Reactant specieID="gaba"/>
<Product specieID="gabaOut"/>
<forwardRate>5e-4</forwardRate>
<reverseRate>0</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<Reaction name = "gaba_GABABR_bind" id="gaba_GABABR_bind">
<Reactant specieID="gaba"/>
<Reactant specieID="GABABR"/>
<Product specieID="gabaGABABR"/>
<forwardRate>5.555e-06</forwardRate>
<reverseRate>0.005</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<Reaction name = "gabaGABABRGi_bind" id="gabaGABABRGi_bind">
<Reactant specieID="gabaGABABR"/>
<Reactant specieID="Gi"/>
<Product specieID="gabaGABABRGi"/>
<forwardRate>0.15e-3</forwardRate>
<reverseRate>0.25e-3</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<Reaction name = "GiaGTP_prod" id="GiaGTP_prod">
<Reactant specieID="gabaGABABRGi"/>
<Product specieID="gabaGABABRGibg"/>
<Product specieID="GiaGTP"/>
<forwardRate>0.125e-3</forwardRate>
<reverseRate>0</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<Reaction name = "gabaGABABRGbg_disso" id="gabaGABABRGbg_disso">
<Reactant specieID="gabaGABABRGibg"/>
<Product specieID="gabaGABABR"/>
<Product specieID="Gibg"/>
<forwardRate>1e-3</forwardRate>
<reverseRate>0</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<!-- 5ae) GABABR + Gi -> GABABRGi -->
<Reaction name = "GABABRGi_bind" id="GABABRGi_bind">
<Reactant specieID="GABABR"/>
<Reactant specieID="Gi"/>
<Product specieID="GABABRGi"/>
<forwardRate>0.075e-3</forwardRate>
<reverseRate>0.125e-3</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<!--Tuomo: added this reaction; otherwise GABABR binding to Gi without ligand would be antagonistic to Gi activation-->
<Reaction name = "gaba_GABABRGi_bind" id="gaba_GABABRGi_bind">
<Reactant specieID="gaba"/>
<Reactant specieID="GABABRGi"/>
<Product specieID="gabaGABABRGi"/>
<forwardRate>5.555e-06</forwardRate>
<reverseRate>0.005</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<!-- 5af and 5ag removed: no production of GiaGTP or Gibg without binding with gaba!-->
<!-- 6b) GiaGTP -> GiaGDP --> <!--Tuomo: the direct conversion replaced by RGS-mediated hydrolysis. Rates taken as such from Zhong et al. 2003 "A Spatial Focusing Model for G Protein Signals"-->
<Reaction name = "GiaGTP_RGS_bind" id="GiaGTP_RGS_bind">
<Reactant specieID="GiaGTP"/>
<Reactant specieID="RGS"/>
<Product specieID="GiaGTPRGS"/>
<forwardRate>2e-6</forwardRate>
<reverseRate>0.002</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<Reaction name = "GiaGTP_RGS_cat" id="GiaGTP_RGS_cat">
<Reactant specieID="GiaGTPRGS"/>
<Product specieID="GiaGDP"/>
<Product specieID="RGS"/>
<forwardRate>30e-3</forwardRate>
<reverseRate>0</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<!-- 7b) GiaGDP + Gbg -> Gi -->
<Reaction name = "Gi_form" id="Gi_form">
<Reactant specieID="GiaGDP"/>
<Reactant specieID="Gibg"/>
<Product specieID="Gi"/>
<forwardRate>1.25e-3</forwardRate>
<reverseRate>0</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<Reaction name = "GIRK_Gibg_bind" id="GIRK_Gibg_bind">
<Reactant specieID="GIRK"/>
<Reactant specieID="Gibg"/>
<Product specieID="GIRKGibg"/>
<forwardRate>14e-6</forwardRate>
<reverseRate>1e-3</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<Reaction name = "GIRKGibg_Gibg_bind" id="GIRKGibg_Gibg_bind">
<Reactant specieID="GIRKGibg"/>
<Reactant specieID="Gibg"/>
<Product specieID="GIRKGibg2"/>
<forwardRate>14e-6</forwardRate>
<reverseRate>1e-3</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<Reaction name = "GIRKGibg2_Gibg_bind" id="GIRKGibg2_Gibg_bind">
<Reactant specieID="GIRKGibg2"/>
<Reactant specieID="Gibg"/>
<Product specieID="GIRKGibg3"/>
<forwardRate>14e-6</forwardRate>
<reverseRate>1e-3</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<Reaction name = "GIRKGibg3_Gibg_bind" id="GIRKGibg3_Gibg_bind">
<Reactant specieID="GIRKGibg3"/>
<Reactant specieID="Gibg"/>
<Product specieID="GIRKGibg4"/>
<forwardRate>14e-6</forwardRate>
<reverseRate>1e-3</reverseRate>
<Q10>0.2</Q10>
</Reaction>
<Reaction name = "VGCC_Gibg_bind" id="VGCC_Gibg_bind">
<Reactant specieID="VGCC"/>
<Reactant specieID="Gibg"/>
<Product specieID="VGCCGibg"/>
<forwardRate>14e-6</forwardRate>
<reverseRate>1e-3</reverseRate>
<Q10>0.2</Q10>
</Reaction>
</ReactionScheme>