The Rho-family of GTPases and their regulators are essential for cytoskeletal reorganization and transcriptional activation in response to extracellular signals. Little is known about what links these molecules to membrane receptors. In the budding yeast Saccharomyces cerevisiae, haploid cells respond to mating pheromone through a G-protein-coupled receptor and the betagamma subunit of the G protein, resulting in arrest of the cell cycle, transcriptional activation, and polarized growth towards a mating partner. The Rho-family GTPase Cdc42 and its exchange factor Cdc24 have been implicated in the mating process, but their specific role is unknown. Here we report the identification of cdc24 alleles that do not affect vegetative growth but drastically reduce the ability of yeast cells to mate. When exposed to mating pheromone, these mutants arrest growth, activate transcription, and undergo characteristic morphological and actin-cytoskeleton polarization. However, the mutants are unable to orient towards a pheromone gradient, and instead position their mating projection adjacent to their previous bud site. The mutants are specifically defective in the binding of Cdc24 to the G-protein betagamma subunit. Our results demonstrate that the association of an exchange factor and the betagamma subunit of a hetero-trimeric G protein links receptor-mediated activation to oriented cell growth.
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| Gene/Complex | Qualifier | Gene Ontology Term | Annotation Extension | Evidence | Source | Assigned On |
|---|---|---|---|---|---|---|
| CDC24 | involved in | chemotropism | part of response to pheromone triggering conjugation with cellular fusion | IMP | SGD | 2018-11-16 |
| CDC24 | involved in | response to pheromone triggering conjugation with cellular fusion | IMP | SGD | 2018-11-16 |
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| Gene | Phenotype | Experiment Type | Mutant Information | Strain Background | Chemical | Details |
|---|---|---|---|---|---|---|
| CDC24 | mating efficiency: decreased | classical genetics | unspecified Allele: cdc24-m1 S189F | Other | Details: 100-fold reduction relative to wildtype; mutants display normal cell cycle arrest, shmoo formation, actin cytoskeleton polarization, and MAPK signalling but are defective prior to fusion |
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| Evidence ID | Analyze ID | Interactor | Interactor Systematic Name | Interactor | Interactor Systematic Name | Allele | Assay | Annotation | Action | Phenotype | SGA score | P-value | Source | Reference | Note |
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Increase the total number of rows showing on this page by using the pull-down located below the table, or use the page scroll at the table's top right to browse through the table's pages; use the arrows to the right of a column header to sort by that column; filter the table using the "Filter" box at the top of the table; click on the small "i" buttons located within a cell for an annotation to view further details about experiment type and any other genes involved in the interaction.