Imported:YPM/Ste12 mediated protein synthesis

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Category:Reactions - Yeast Pheromone Response Model Back to main model page



Ste12 mediated protein synthesis

  • Ste3 expression is rapidly upregulated in response to treatment with a-factor. Hagen and Sprague. 1984 PMID 6436496
  • Activity of pheromone-responsive reporter gene (8 tandem copies of PRE driving lacZ) in absence of pheromone is altered by pathway mutations. Hasson et al. 1994 PMID 8289786
    • down about 10-fold when ste4, ste18, or ste5 is mutated
    • down about 100-fold when ste7, ste11, or ste12 is mutated
    • up about 3-fold when ste2 is mutated

Reaction Definition

When Ste12 mediated protein synthesis is included in a model, the synthesis rates of several proteins specified on elsewhere in the wiki must be decreased such that the steady-state abundance of each protein is properly maintained. Basal activation of Ste12 (in the absence of pheromone) will result in some additional level of synthesis of the proteins listed below, and so the synthesis rates of these proteins must be decreased elsewhere commensurately. See Protein dilution/synthesis due to cell growth for synthesis of Dig2, Far1, Fus3, Msg5, Ptp, and Ste12. See Gpa1 synthesis/degradation, Sst2 synthesis/degradation and Ste2 synthesis/endocytosis/degradation for synthesis of Gpa1, Sst2 and Ste2.

As detailed on the Ste12 phosphorylation page, we are assuming that Ste12 does not need to be phosphorylates by Fus3 or Kss1 to be active, and that being free from Dig1 and Dig2 is sufficient for Ste12 to initiate gene expression.

Rather than model the details of transcription and translation, we shall approximate the process with saturation kinetics of the form Ste12 -> Ste12 + protein, occuring at a rate of kcat*Ste12/(Km+Ste12). The BioNetGen expression that defines this rate law is Sat(kcat,Km).

<modelRxnFull><modelRxnRule>

Ste12(Dig1_site, Dig2_site, MAPK_site) -> 
Ste12(Dig1_site, Dig2_site, MAPK_site) + Dig2(Ste12_site, MAPK_site, PO4_site~none)

</modelRxnRule>

<modelRxnFull><modelRxnRule>

Ste12(Dig1_site, Dig2_site, MAPK_site) -> 
Ste12(Dig1_site, Dig2_site, MAPK_site) + Far1(MAPK_site, S87~none, T306~none)

</modelRxnRule>

<modelRxnFull><modelRxnRule>

Ste12(Dig1_site, Dig2_site, MAPK_site) -> 
Ste12(Dig1_site, Dig2_site, MAPK_site) + Fus3(docking_site, T180~none, Y182~none)

</modelRxnRule>

<modelRxnFull><modelRxnRule>

Ste12(Dig1_site, Dig2_site, MAPK_site) -> 
Ste12(Dig1_site, Dig2_site, MAPK_site) + Gpa1(Ste2_site, Ste4_site, nucleotide~GDP)

</modelRxnRule>

<modelRxnFull><modelRxnRule>

Ste12(Dig1_site, Dig2_site, MAPK_site) -> 
Ste12(Dig1_site, Dig2_site, MAPK_site) + Msg5(MAPK_site)

</modelRxnRule>

<modelRxnFull><modelRxnRule>

Ste12(Dig1_site, Dig2_site, MAPK_site) -> 
Ste12(Dig1_site, Dig2_site, MAPK_site) + Ptp(MAPK_site)

</modelRxnRule>

<modelRxnFull><modelRxnRule>

Ste12(Dig1_site, Dig2_site, MAPK_site) -> 
Ste12(Dig1_site, Dig2_site, MAPK_site) + Sst2(Ste2_site, MAPK_site, S539~none)

</modelRxnRule>

<modelRxnFull><modelRxnRule>

Ste12(Dig1_site, Dig2_site, MAPK_site) -> 
Ste12(Dig1_site, Dig2_site, MAPK_site) + Ste2(Pheromone_site, Gpa1_site, Sst2_site, Yck_site, S338_S339~none)

</modelRxnRule>

<modelRxnFull><modelRxnRule>

Ste12(Dig1_site, Dig2_site, MAPK_site) -> 
Ste12(Dig1_site, Dig2_site, MAPK_site) + Ste12(Dig1_site, Dig2_site, MAPK_site)

</modelRxnRule>