9317499 Clancy Sporulation in the yeast, Saccharomyces cerevisiae, is a cell-type specific response to nutritional signals. Only MATa/MAT alpha diploids can sporulate; cells that contain only one of the MAR alleles, or mutations at MAR, cannot do so. Work in several laboratories has identified key regulators through which the mating type locus controls the sporulation response. Of central importance are an activator of meiosis (IME1) that is highly expressed in starved MATa/MAT alpha diploids, and a repressor of meiosis (RME1) that is poorly expressed in these cells this work is aimed at understanding the regulation and function of a newly-described activator, called IME4. Like IME1, IME4 is normally expressed only in starved MATa/MAT alpha cells and not in the other cell types. Unlike IME1, however, IME4 is not regulated by RME1 repressor. Rather, a different intermediate is used to transmit mating type information to IME4. One important goal of this work is to understand the nature and identity of this unknown intermediate, and the targets at IME4 upon which it acts. IME4 is formally upstream of IME1 in this genetic pathway, because strains that lack IME4 do not express IME1 and do not sporulate. However, mutations that allow expression of IME1 without IME4 do not restore sporulation. This suggests that IME4 plays additional roles in sporulation, apart from stimulating IME1 expression. We plan to define these roles genetically, by identifying suppressors of this downstream defect and by defining mutation phenotypes more precisely. To better understand the function of IME4, we will identify proteins that interact with the IME4 product, and determine the location of the product in the cells. %%% This research will aid in our understanding of gene expression in yeast, an organism of important to the biotechnology industry. In addition, it will help to train a number of undergraduate students in current techniques in modern molecular biology. ***

National Science Foundation (NSF)
Division of Molecular and Cellular Biosciences (MCB)
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Philip Harriman
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University of New Orleans
New Orleans
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