Quantitative Measure of Scaffold Protein Membrane Recruitment in Live Cells

ALAN BUSH; ALEJANDRO COLMAN LERNER

Toronto

Congreso; International Conference on Systems Biology; 2012

International Society of Systems Biology

The yeast pheromone response pathway is a prototypical signal transduction system [1] that has been studied for many years from a biochemical, genetic and recently from a modeling perspective. It is comprised of a G protein coupled receptor and a MAPK cascade. At the interface between these two modules lies the scaffold protein Ste5, which simultaneously binds free Gβγ heterodimer and the components of the MAPK cascade. Here we present a quantitative microscopy method developed to measure membrane recruitment of Ste5, an essential step in the propagation of the signal. Using this method we estimated the effective binding affinity of Ste5 for its membrane associated binding sites. Interestingly enough, the effective affinity is modulated during the response from an initial high affinity state (Kd