title: Activation of Gal4p by galactose-dependent interaction of galactokinase and Gal80p.
abstract: Yeast galactokinase (Gal1p) is an enzyme and a regulator of transcription. In addition to phosphorylating galactose, Gal1p activates Gal4p, the activator of GAL genes, but the mechanism of this regulation has been unclear. Here, biochemical and genetic evidence is presented to show that Gal1p activates Gal4p by direct interaction with the Gal4p inhibitor Gal80p. Interaction requires galactose, adenosine triphosphate, and the regulatory function of Gal1p. These data indicate that Gal1p-Gal80p complex formation results in the inactivation of Gal80p, thereby transmitting the galactose signal to Gal4p.
authors.affiliation: Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Germany.
authors.forename: F T
authors.initials: FT
authors.lastname: Zenke
authors.forename: R
authors.initials: R
authors.lastname: Engles
authors.forename: V
authors.initials: V
authors.lastname: Vollenbroich
authors.forename: J
authors.initials: J
authors.lastname: Meyer
authors.forename: C P
authors.initials: CP
authors.lastname: Hollenberg
authors.forename: K D
authors.initials: KD
authors.lastname: Breunig
mesh_terms: D000595:Amino Acid Sequence; D003067:Coenzymes / Q000378:metabolism; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000378:metabolism*; D005686:Galactokinase / Q000235:genetics / Q000378:metabolism*; D005690:Galactose / Q000378:metabolism*; D007716:Kluyveromyces / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D012097:Repressor Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D003067:Coenzymes; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; C055002:GAL80 protein, S cerevisiae; C099289:Gal3 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D005686:Galactokinase; D005690:Galactose