title: Molecular characterization of yeast regulatory gene CAT3 necessary for glucose derepression and nuclear localization of its product.
abstract: The yeast regulatory gene CAT3 has an essential function for the depression of several glucose-repressible enzymes. Therefore, cat3 mutants are unable to grow on maltose or on non-fermentable carbon sources. Unlike the point mutants isolated previously, cat3 null allele strains also failed to utilize raffinose or galactose as sole carbon sources. Sequencing of an 1.6-kb HindIII-BglII fragment complementing cat3 mutations revealed an open reading frame of 322 codons, size of which is in good agreement with the 1.3-kb size of mRNA. No significant similarities with previously sequenced genes could be detected. CAT3-lacZ fusions confirmed the proposed reading frame. A CAT3-lacZ fusion encoding 307 amino acids of CAT3 was able to complement the growth defects of cat3 point mutants and null allele strains. Assay of beta-galactosidase activity under different growth conditions indicated a constitutive expression of the CAT3 gene product. Cellular fractionation studies showed the nuclear localization of the CAT3 protein.
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D002467:Cell Nucleus; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004274:DNA, Recombinant; D004591:Electrophoresis, Polyacrylamide Gel; D004794:Enzyme Repression; D005656:Fungal Proteins / Q000032:analysis; D005786:Gene Expression Regulation; D005809:Genes, Regulator; D005947:Glucose / Q000235:genetics*; D015151:Immunoblotting; D007763:Lac Operon; D008969:Molecular Sequence Data; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D004274:DNA, Recombinant; D005656:Fungal Proteins; D005947:Glucose