Human pancreatic beta-cell glucokinase (GKbeta) is the main glucose phosphorylating enzyme in pancreatic beta-cells. It shares several structural, catalytic and regulatory properties with hexokinase 2 (Hxk2) from Saccharomyces cerevisiae. In fact, it has been previously described that expression of GKbeta in yeast could replace Hxk2 in the glucose signalling pathway of S. cerevisiae. In this study we report that GKbeta exerts its regulatory role by association with the yeast transcriptional repressor Mig1; the presence of Mig1 allows GKbeta to bind to the SUC2 promoter, helping in this way in the maintenance of the repression of the SUC2 gene under high-glucose conditions. Since a similar mechanism has been described for the yeast Hxk2, our findings suggest that the function of the regulatory domain present in these two proteins has been conserved throughout evolution. In addition, we report that GKbeta is enriched in the yeast nucleus of high-glucose growing cells, whereas it shows a mitochondrial localization upon removal of the sugar. However, GKbeta does not exit the nucleus in the absence of Mig1, suggesting that Mig1 regulates the nuclear exit of GKbeta under low-glucose conditions. We also report that binding of GKbeta to Mig1 allows the latter protein to be located at the mitochondrial network under low-glucose conditions.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|