FIG. 4.

Localization of DNA binding activity to a 150-bp DdeI fragment in the upstream regulatory region of yps 21:E-9. Nuclear (Nucl) and cytoplasmic (Cyto) extracts (40 μg) from the mycelial phases of G217B and Downs were evaluated by Southwestern analysis with ³²P-labelled targets derived from the 395-bp PCR-amplified yps 21:E-9 regulatory region from G217B. The amplified probe was digested with DdeI to liberate labelled fragments of 109, 150, and 136 bp. As indicated in the diagram, the 135-bp fragment contains the ATG codon while the transcription start site mapped by S1 analysis is within the 150-bp fragment flanked by DdeI sites. The asterisk denotes the location of the single TCCTTTTTTT motif observed in this DNA ligand.