The ubiquitin ligase SCF(Grr1) is required for Gal2p degradation in the yeast Saccharomyces cerevisiae.
F-box proteins represent the substrate-specificity determinants of the SCF ubiquitin ligase complex. We previously reported that the F-box protein Grr1p is one of the proteins involved in the transmission of glucose-generated signal for proteolysis of the galactose transporter Gal2p and fructose-1,6-bisphosphatase. In this study, we show that the other components of SCF(Grr1), including Skp1, Rbx1p, and the ubiquitin-conjugating enzyme Cdc34, are also necessary for glucose-induced Gal2p degradation. This suggests that transmission of the glucose signal involves an SCF(Grr1)-mediated ubiquitination step. However, almost superimposable ubiquitination patterns of Gal2p observed in wild-type and grr1Delta mutant cells imply that Gal2p is not the primary target of SCF(Grr1) ubiquitin ligase. In addition, we demonstrate here that glucose-induced Gal2p proteolysis is a cell-cycle-independent event.
Horak
J
J
Institute of Physiology, Department of Membrane Transport, Academy of Science of the Czech Republic, 142 20 Prague, Czech Republic.
Wolf
D H
DH
D001673:Biodegradation, Environmental; D002453:Cell Cycle / Q000502:physiology; D044783:F-Box Proteins; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D025941:Protein Interaction Mapping; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
D044783:F-Box Proteins; C106901:GAL2 protein, S cerevisiae; D009004:Monosaccharide Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; C071032:GRR1 protein, S cerevisiae; D044843:SKP Cullin F-Box Protein Ligases; D044767:Ubiquitin-Protein Ligases