A GTP-exchange factor required for cell orientation

摘要: The Rho-family of GTPases and their regulators are essential for cytoskeletal reorganization transcriptional activation in response to extracellular signals1,2. Little is known about what links these molecules membrane receptors. In the budding yeast Saccharomyces cerevisiae, haploid cells respond mating pheromone through a G-protein-coupled receptor βγ subunit G protein3, resulting arrest cell cycle, activation, polarized growth towards partner4,5. GTPase Cdc42 its exchange factor Cdc24 have been implicated process6,7, but specific role unknown. Here we report identification cdc24 alleles that do not affect vegetative drastically reduce ability mate. When exposed pheromone, mutants growth, activate transcription, undergo characteristic morphological actin-cytoskeleton polarization. However, unable orient gradient, instead position projection adjacent previous bud site. specifically defective binding G-protein subunit. Our results demonstrate association an hetero-trimeric protein receptor-mediated oriented growth.