Saccharomyces_A

The coregulators further repress expression of the

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Unformatted text preview: ly function in both a cells and cells but not in a/ diploids, such as HO (see later). The coregulators further repress expression of the rme1 gene. The presence of the Rme1 protein inhibits the meiotic pathway; its absence, therefore, confers competence for meiosis. Finally, the 2 regulator alone represses a-specific genes (asg genes). The net result is that a/ cells are sterile but competent to undergo meiosis. Verification of the 1- 2 hypothesis, which was proposed on the basis of mutant analysis, has come from various molecular studies. Molecular analyses of RNA in mutant and wild-type cells have shown that the a1, a2, and a1 gene products act at the level of transcription. MATa1 mutants (lacking a functional 1 gene) do not transcribe the a-specific genes known as STE3 (which encode an a pheromone receptor) and MF 1 and MF 2 (which encode pheromone); normal cells do express these genes. Similarly, MAT 2 cells (lacking a functional 2 gene) transcribe and produce functional products of the a-specific genes that encode an pheromone receptor and a har06584_refA_001-020 10 11/13/06 09:12 PM Page 10 Reference A Saccharomyces cerevisiae: G...
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