They are purifying Sst2 and Gpa1 from Saccharomyces cerevisiae with the goal of investigating how the Sst2-G protein interaction is regulated, and what domains of Sst2 mediate this interaction. In the course of their experiments, they observed a marked decrease in the electrophoretic mobility of Gst tagged Sst2 purified from pheromone-treated vs. untreated cells and will be evaluating the likely role of protein phosphorylation as the modification event attendant those observed mobility changes.