Figure 1.

Reporter genes for monitoring mitochondrial (a) or nuclear (b) microsatellite stability in yeast. (a) Reporter gene for monitoring mitochondrial microsatellite stability (cox3∷arg8^m). ARG8^m is a derivative of the yeast ARG8 gene in which the codon usage has been altered to be consistent with mitochondrial expression (16). This gene is expressed by using the COX3 transcriptional and translational signals in mtDNA (thin line). COX3 protein coding sequences are represented by the solid box. The fusion protein is processed posttranslationally at the site indicated by the arrow. Microsatellite sequences [in-frame or out-of-frame insertions of poly(AT) or poly(GT)] were inserted at the designated AccI site. (b) Reporter gene for monitoring nuclear microsatellite stability (20). The components of this fusion gene encoding a protein with wild-type Ura3p activity are GAL1,10 promoter (shaded box), N-terminal amino acids derived from LYS2 (solid box), HIS4-derived amino acids (striped box), and URA3-derived sequences (open box). Microsatellite sequences [in-frame insertions of poly(AT) or poly(GT)] were inserted at the designated BglII site. These plasmids were integrated into the LEU2 locus in a strain with a ura3 mutation.