Imported:YPM/Ste4:Ste18/Ste20 interaction

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

---

Ste4:Ste18 interactions with Ste20

• Mutational analysis suggests that Ste5 and Ste20 may interact with Ste4 residues on opposite sides of the Ste4/Ste18 coiled-coil. Dowell et al. 1998 PMID 9832519
  • This suggests that Ste5 and Ste20 may be able to simultaneously bind a single Ste4:Ste18.
  • These results are partially confirmed by NMR studies of the interaction between pepetides from Ste20 and Ste4 (Bhattacharjya et al. 2006 PMID 16870141) and additional mutant analysis (Leeuw et al. 1998 PMID 9428767).

• Ste20 interacts with Ste4 in a pheromone-dependent manner. Leeuw et al. 1998 PMID 9428767

Reaction Definition

Assumptions:

• Ste20 and Ste5 can bind simultaneously to the the same Ste4:Ste18 monomer.
• Ste20 cannot bind Ste4:Ste18 when Ste4:Ste18 is bound by Gpa1, and vice versa.
• Ste20 binds Ste4:Ste18 with the same affinity regardless of whether the Ste4:Ste18 has previously bound to Ste5 or a complex of Ste5 with kinases.

<modelRxnFull><modelRxnRule>

Ste4(Gpa1_site, Ste20_site) + Ste20(Ste4_site, Ste11_site) <-> 
    Ste4(Gpa1_site, Ste20_site!1).Ste20(Ste4_site!1, Ste11_site)

</modelRxnRule>

• Forward rate constant <modelRxnParam>kon_Ste4_Ste20</modelRxnParam>
• Reverse rate constant <modelRxnParam>koff_Ste4_Ste20</modelRxnParam></modelRxnFull>