Glucose-dependent and -independent signalling functions of the yeast glucose sensor Snf3

The yeast Snf3 protein has been described to function as a sensor for low c oncentrations of extracellular glucose. We have found that Snf3 is able to transduce a signal in the complete absence of extracellular glucose. High b asal activity of the HXT7 promoter during growth on ethanol required Snf3 a s well as other components of the signalling pathway activated by Snf3. Mor eover, the C-terminal domain of Snf3 was sufficient to complement the role of Snf3 in this regulation. As the C-terminal tail of Snf3 interacted with other components at the plasma membrane independent of the carbon source, o ur data suggest that Snf3 is involved in signalling complexes which can be activated by other signals than extracellular glucose. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All r ights reserved.