Single Cell Model

The single-cell pathway model of our system is composed of 4 modules, which are responsible for routing the signal from the receptor to the GFP sythesis. The mathematical model is developed on a scheme favoring the temporal order of processes, based on the current understanding of the pheromone signalling pathway from [1][2][3] and on the feedback received from the experimentalists on the expected behaviour of the pathway, taking into consideration the aspects relevant to our project.

Model of the G - Protein cycle

The concentration of free G-beta-gamma dimer is crucial for the activation of the MAP kinase cascade which in turn activates the expression of the GFP. The promoter used for the receptor and the initial concentration of the ligand were thus crucial parameters for the activation of the G-Protein Cycle. A model of the G-Protein cycle by Yi et al [1] was used to analyze the effects of the different promoter strengths of the receptor and the effects of various initial concentrations on the activation of the G-Protein cycle.

Model of the Yeast Pheromone Response

A model of the yeast pheromone response by Kofahl and Klipp[2] was used to test the effects of knockout on the transcription factor Ste12.

Model of the Snifformyces Pathway

The model of the G-protein cycle lacked the description of MAP kinase cascade and the gene expression module.The model of the yeast pheromone response though was detailed with the exclusion of the gene expression module but suffered from a very high degree of complexity. Fitting the limited data available from the experiments to the highly complex pathway model in would not have been feasible due to the number of parameters.

The above drawbacks motivated us to build a model, which would capture the crucial components of the project with a reduced degree of complexity i.e with lesser parameters to be identified. Combining the knowledge from [1] and [2]. We built a new model of the pathway based on [3. The initial rates were obtained by fitting the model to the data in [4]. The model is capable of reproducing the Fus3 dynamics.