The rapid response of Saccharomyces cerevisiae to glucose is regulated by several pathways. The Snf3/Rgt2-Rgt1 (SRR) pathway detects extracellular glucose and regulates induction of HXT gene expression, allowing the cells quickly to import glucose. In the absence of glucose, Mth1 acts as a co-repressor with the Rgt1 DNA-binding protein to repress HXT gene expression. Upon addition of glucose, Mth1 exits the nucleus, interacts with the glucose sensors, where it is phosphorylated by the casein kinases Yck1/2. Mth1 is consequently ubiquitinated and then degraded, relieving repression of HXT gene expression. We determined by a heterokaryon assay that shuttling of Mth1 between the nucleus and the cytoplasm is not regulated by glucose. Inhibiting shuttling by adding an NLS to Mth1 prevented derepression of HXT1 expression. Adding an NES to Mth1 prevents its degradation but does not interfere with the induction of HXT1 expression. These results suggest that Mth1 is degraded in the nucleus and must be exported from the nucleus for HXT expression to be induced. Intrinsic NLS and NES sequences must be present in Mth1 to permit its shuttling between the nucleus and the cytoplasm. We located one NLS through truncation and internal deletion experiments. Previous studies identified eight serine residues in conserved Yck1/2 consensus phosphorylation sequences in Mth1 required for its degradation. We found that phosphorylation of only four of these eight serine residues, most importantly Ser133, are necessary for degradation of Mth1. Therefore, nuclear translocation and phosphorylation of Mth1 are required for its degradation and the ability of Saccharomyces cerevisiae to rapidly respond to glucose.