We investigated whether or not the potential clock gene, GTS1, of the yeast Saccharomyces cerevisiae, shows pleiotropic effects on the yeast cellular processes. We tested the efect of the Gts1 protein on heat tolerance, sporulation and life-span, by characterizing the phenotypes of transformants with different copy numbers of the gene. We found that the Gts1 protein affects the capacity of heat tolerance in the stationary phase and the speed leading to sporulation in a gene-dose dependent manner, and that both inactivation and overexpression of the gene shortened the life-span of yeast. These results supported the notion that GTS1 affects the biological clock of the yeast S. cerevisiae, although this cannot be definitively concluded because the strain cannot be synchronized with circadian or ultradian rhythms.