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Unformatted text preview: velopment in multicellular eukaryotes. The MAT Locus Controls Expression
of the Genes That Determine Cell Type
A cell with MATa information at the MAT locus has an a
mating type. By contrast, a cell carrying MAT information at the MAT locus has an mating type. What at the
MAT locus determines these different mating types?
Clues to the role of the MAT locus ﬁrst emerged from
mutant analyses. When sterile mutants of cells were isolated, one class of mutants had defects at the MAT locus. har06584_refA_001-020 11/4/06 10:10 AM Page 9 A.2 Cell Differentiation in Yeast: Mechanisms for Determining Cell Type Surprisingly, the MAT mutations fell into two complementation groups, indicating that instead of a single gene at
the MAT locus, there are two genes, 1 and 2. Mutations
in the 1 and 2 complementation groups produce different molecular effects, which inform us of the roles of the
genes. Strains carrying 1 mutations fail to synthesize
pheromone, a protein normally made by cells. Strains
carrying 2 mutations synthesize a pheromone but degrade
it before it can be secreted; normally, only a cells express
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This note was uploaded on 10/03/2013 for the course BI 206 taught by Professor Celenza during the Spring '08 term at BU.
- Spring '08