Pheromone-responsive MAPK scaffold; couples activation of the G-protein-coupled pheromone receptor to MAPK activation; intramolecular interaction of PH and VWA domains blocks activation of the assembled signaling cascade (Ste11p, Ste7p and Fus3p) under basal conditions; Gβ-γ (Ste4p-Ste18p)-dependent docking at the plasma membrane and PI(4,5)P2 binding by the PH domain relieves autoinhibition, activating the pathway; interacts with Gα (Gpa1p) to enhance the efficiency of polarity site alignment