Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Saccharomyces cerevisiae regulatory genes CAT1 and CAT3 constitute a positive control circuit necessary for derepression of gluconeogenic and disaccharide-utilizing enzymes. Mutations within these genes are epistatic to hxk2 and hex2, which cause defects in glucose repression. cat1 and cat3 mutants are unable to grow in the presence of nonfermentable carbon sources or maltose. Stable gene disruptions were constructed inside these genes, and the resulting growth deficiencies were used for selecting epistatic mutations. The revertants obtained were tested for glucose repression, and those showing altered regulatory properties were further investigated. Most revertants belonged to a single complementation group called cat4. This recessive mutation caused a defect in glucose repression of invertase, maltase, and iso-1-cytochrome c. Additionally, hexokinase activity was increased. Gluconeogenic enzymes are still normally repressible in cat4 mutants. The occurrence of recombination of cat1::HIS3 and cat3::LEU2 with some cat4 alleles allowed significant growth in the presence of ethanol, which could be attributed to a partial derepression of gluconeogenic enzymes. The cat4 complementation group was tested for allelism with hxk2, hex2, cat80, cid1, cyc8, and tup1 mutations, which were previously described as affecting glucose repression. Allelism tests and tetrad analysis clearly proved that the cat4 complementation group is a new class of mutant alleles affecting carbon source-dependent gene expression.
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PMID:Extragenic suppressors of yeast glucose derepression mutants leading to constitutive synthesis of several glucose-repressible enzymes. 200 6

The expression of gluconeogenic fructose-1,6-bisphosphatase (encoded by the FBP1 gene) depends on the carbon source. Analysis of the FBP1 promoter revealed two upstream activating elements, UAS1FBP1 and UAS2FBP1, which confer carbon source-dependent regulation on a heterologous reporter gene. On glucose media neither element was activated, whereas after transfer to ethanol a 100-fold derepression was observed. This gene activation depended on the previously identified derepression genes CAT1 (SNF1) (encoding a protein kinase) and CAT3 (SNF4) (probably encoding a subunit of Cat1p [Snf1p]). Screening for mutations specifically involved in UAS1FBP1 derepression revealed the new recessive derepression mutation cat8. The cat8 mutants also failed to derepress UAS2FBP1, and these mutants were unable to grow on nonfermentable carbon sources. The CAT8 gene encodes a zinc cluster protein related to Saccharomyces cerevisiae Gal4p. Deletion of CAT8 caused a defect in glucose derepression which affected all key gluconeogenic enzymes. Derepression of glucose-repressible invertase and maltase was still normally regulated. A CAT8-lacZ promoter fusion revealed that the CAT8 gene itself is repressed by Cat4p (Mig1p). These results suggest that gluconeogenic genes are derepressed upon binding of Cat8p, whose synthesis depends on the release of Cat4p (Mig1p) from the CAT8 promoter. However, gluconeogenic promoters are still glucose repressed in cat4 mutants, which indicates that in addition to its transcription, the Cat8p protein needs further activation. The observation that multicopy expression of CAT8 reverses the inability of cat1 and cat3 mutants to grow on ethanol indicates that Cat8p might be the substrate of the Cat1p/Cat3p protein kinase.
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PMID:CAT8, a new zinc cluster-encoding gene necessary for derepression of gluconeogenic enzymes in the yeast Saccharomyces cerevisiae. 789 85