The hexokinase isoenzyme PII of Saccharomyces cerevisiae ia a protein kinase.
The HXK2 gene product has an important role in controlling carbon catabolite repression in Saccharomyces cerevisiae. We have raised specific antibodies against the hexokinase PII protein and have demonstrated that it is a 58 kDa phosphoprotein with protein kinase activity. The predicted amino acid sequence of the HXK2 gene product has significant homology to the conserved catalytic domain of mammalian and yeast protein kinases. Protein kinase activity was located in a different domain of the protein from the hexose-phosphorylating activity. The hexokinase PII protein level remained unchanged in P2T22D mutant cells (hxk1 HXK2 glk1) growing in a complex medium with glucose. The protein kinase activity of hexokinase PII is regulated by the glucose concentration of the culture medium. Exit from the carbon catabolite repression phase and entry into derepression phase may be controlled, in part, by modulation of the 58 kDa protein kinase activity by changes in cyclic AMP concentration.
Herrero
P
P
Departmento de Biología Funcional, Universidad de Oviedo, Spain.
Fernández
R
R
Moreno
F
F
D000595:Amino Acid Sequence; D000818:Animals; D000908:Antibodies, Fungal / Q000276:immunology; D000242:Cyclic AMP / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics / Q000276:immunology; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D005800:Genes, Fungal; D005947:Glucose / Q000494:pharmacology; D006593:Hexokinase / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D007527:Isoenzymes / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D008322:Mammals / Q000235:genetics; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000235:genetics / Q000276:immunology / Q000502:physiology; D011494:Protein Kinases / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000276:immunology; D012689:Sequence Homology, Nucleic Acid
D000908:Antibodies, Fungal; D005656:Fungal Proteins; D007527:Isoenzymes; D010750:Phosphoproteins; D000242:Cyclic AMP; D011494:Protein Kinases; D006593:Hexokinase; D005947:Glucose