Figure 6.

Model of the mating pathway with three distinct branches leading to vacuolar targeting, transcription, and morphogenesis. Binding of mating pheromone to its receptor Ste2 triggers activation of the G protein. Vacuolar targeting is initiated by Gpa1–GTP at endosomal membranes, requires the PI 3-kinase Vps34 and the terminal MAPK Fus3 (but not Kss1), and is positively regulated by the F-box protein Dia2. In contrast, new gene transcription and morphogenesis are initiated by the Gβγ subunits at the plasma membrane, transmitted by either Fus3 or Kss1, and negatively regulated by the F-box protein Ucc1. Proper morphogenesis is initiated by Gβγ, mediated by the small G-protein Cdc42, and is regulated by the F-box protein, Pfu1.