PHEROMONE SIGNALING AND POLARIZED MORPHOGENESIS IN YEAST

Yeast cells respond to mating pheromones by activating a signal transd uction pathway involving a seven transmembrane receptor/G protein comp lex linked to a mitogen-activated protein kinase module. Regulation of the G protein signal is controlled by the receptor and Sst2p; Sst2p m ay function as a GTPase-activating protein for the G protein ct subuni t. The Ste20 kinase acts in the linkage between the G protein and the MAP kinase module. Experiments suggest that binding of the Rho-like GT Pase Cdc42p to Ste20p is not required for the mating response, yet is needed for the pseudohyphal growth response which involves many of the same kinases.