FIG. 1.

Structures of EFB1 episomal constructs expressing the tagged U18 snoRNA. The diagrammatic representation shows plasmid pGALU18, containing the transcriptional unit of the EFB1 gene between the GAL1 promoter and the CYC1 terminator, and its mutant derivatives. The dark box within the U18 snoRNA represents the tag sequence. All of the mutations introduced are shown in boldface letters and are aligned with the corresponding wild-type (wt) sequences. G₁₈ indicates the site of insertion of the poly(G) cassette. The different oligonucleotides utilized in the work are indicated by arrows in the regions where they hybridize. The lengths of the different portions of the construct are indicated in nucleotides. pA indicates the polyadenylation site within the CYC1 terminator (term).