G-Protein Signaling and Cell Polarization How do cells reliably project and move in the correct direction? It is a challenging task given the inherent external and internal uncertainties. In the budding yeast, S. cerevisiae, haploid cells polarize and project toward their mating partner in response to peptide mating pheromones. The well-characterized signal transduction network mediating this behavior involves both heterotrimeric and small G-protein signaling with many features conserved in higher eukaryotes. The goal of this research is to demonstrate how the carefully controlled dynamics of G-protein signaling are essential for robust cell polarization. The approach is to use a combination of quantitative experiments and mathematical modeling. Some of the research topics in the lab include the following: • Dynamics and control of the heterotrimeric G-protein cycle • A quantitative description of cell polarization • Modeling yeast mating Robustness of Biological Systems Why are living systems so complicated? The simple answer is that much of this complexity arises from the control structures necessary to ensure robustness. We wish to characterize the regulation of biological networks using control theory. Some of the research topics under investigation include the following: • Limits to robustness and the Bode Integral Fragility Formula (BIFF) • Integral control, the Internal Model Principle, and homeostasis • Optimal control strategies in signal transduction networks |