Abstract
Yeast mutants deficient in orotidine-5'-phosphate (OMP) pyrophosphorylase activity have been obtained. The gene encoding this enzyme is unlinked to the four pyrimidine genes previously described. The specific activity of OMP pyrophosphorylase remains constant under all of the physiological conditions used to repress, to derepress, or to induce pyrimidine biosynthesis. This enzyme appears, therefore, to escape the scheme of regulation by mixed repression and induction controlling the other enzymes of the pyrimidine pathway.
MeSH terms
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Amidohydrolases / metabolism
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Amino Acids / pharmacology
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Aspartic Acid / pharmacology
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Carbamates / pharmacology
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Carboxy-Lyases / metabolism
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Cell-Free System
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Culture Media
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Enzyme Induction
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Enzyme Repression
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Fluorouracil / pharmacology
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Genes
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Genetic Complementation Test
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Genetics, Microbial
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Mutation
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Orotic Acid / metabolism
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Oxidoreductases / metabolism
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Pentosyltransferases / metabolism*
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Pyrimidines / biosynthesis
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Saccharomyces / enzymology*
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Saccharomyces cerevisiae / enzymology
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Saccharomyces cerevisiae / growth & development
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Saccharomyces cerevisiae / metabolism
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Spectrophotometry
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Transferases / metabolism
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Uracil / analogs & derivatives
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Uracil / pharmacology
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Uracil Nucleotides / biosynthesis
Substances
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Amino Acids
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Carbamates
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Culture Media
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Pyrimidines
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Uracil Nucleotides
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Aspartic Acid
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Uracil
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Orotic Acid
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Oxidoreductases
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Transferases
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Pentosyltransferases
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Amidohydrolases
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Carboxy-Lyases
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Fluorouracil