Effect of Ty1-neo insertions on pre-sup2+btarget gene expression. (A) Representative RNA blots of pre-sup2+b and U14 transcripts from cells harboring plasmids with a Ty1-neo inserted at position t or x (* indicates the presence of a G56 mutation in box B of thesup2+b gene, rendering it transcriptionally inactive). Multiple yeast transformants containing the same Ty1-neo target plasmid were analyzed. RNA was also isolated from cells lacking the sup2+b target plasmid (-target). RNA blots are not shown for the target plasmids containing Ty1-neo insertions at positions u and w. The ratio ofsup2+b to U14 RNA was determined for each sample, and normalized for plasmid copy number. As multiple species of pre-sup2+b transcript were present, indicated by the bracketed region, the sum of all bands in this region was measured. (B) RNA levels are relative to that of a target plasmid lacking a Ty1-neo insertion (-Ty1).
