The HTR1 gene is a dominant negative mutant allele of MTH1 and blocks Snf3- and Rgt2-dependent glucose signaling in yeast.

Saccharomyces cerevisiae HTR1 mutants are severely impaired in the uptake of glucose. We have cloned dominant HTR1 mutant alleles and show that they encode mutant forms of the Mth1 protein. Mth1 is shown to be involved in carbon source-dependent regulation of its own, invertase and hexose transporter gene expression. The mutant forms block the transduction of the Snf3- and Rgt2-mediated glucose signals upstream of the Rgt1 transcriptional regulator.