The TAN1 gene is required for growth of a sup61-T47:2C strain. (A) Wild-type (UMY2220), sup61-T47:2C (UMY2256), tan1Δ (UMY2874), and sup61-T47:2C tan1Δ (derived from UMY2951) strains carrying the low copy URA3 plasmid pRS316-TAN1 were grown in synthetic complete medium (SC), serially diluted, spotted onto SC and SC+5-fluoro-orotic acid (5-FOA) plates, and incubated at 30°C for 2 d. Cells containing a URA3 plasmid are unable to grow on 5-FOA–containing media (Boeke et al. 1984). (B) The sup61-T47:2C tan1Δ strain in A transformed with pRS425 or pRS425-sup16+ (high copy LEU2 plasmids) was grown in SC-Leu medium, serially diluted, spotted onto SC-Leu and SC-Leu+5-FOA plates, and incubated for 3 d at 30°C.