Yeast cells use glycerol as a carbon source as well as for osmoregulation (Hohmann, 2002). Glycerol uptake is mediated by the symporter Stl1 (sugar transporter-like protein) (Ferreira, 2005) (Fig. 1). Following its uptake, glycerol is converted to glycerol-3-phosphate by the cytoplasmic kinase Gut1 before entering the mitochondria. The mitochondrial FAD-dependent glycerol-3-phosphate dehydrogenase, encoded by the GUT2 gene, is responsible for the conversion to dihydroacetone phosphate, which can enter the glycolytic or the gluconeogenic pathway. Both GUT1 and GUT2 are expressed with cells grown in the presence of glycerol or ethanol while these genes are repressed in the presence of glucose