Fig. 4.

Defining the boundaries of the sgRNAβ2 promoter. Protoplasts were transfected with the α and γ genomic RNAs and RNAβ derivatives containing a 48-nt deletion (β1−34/+14) to eliminate sgRNAβ1 promoter activity. The deletions are numbered according to the sgRNAβ2 transcription start site, which is illustrated by the arrow. Total nucleic acids were extracted at 20 h posttransfection and processed as described in Fig. 2, except that hybridizations were performed with a β-specific riboprobe (β SspI/BglII) derived from sequence upstream of the sgRNA2 promoter region. (A) Large-scale deletion mapping of the sgRNAβ2 promoter is shown on the blot to the left. To define the region between −70 and −53 further, 6-nt deletions were constructed and are shown on the blot to the right. (B) Small-scale mapping of the sgRNAβ2 promoter. The sequence represents the negative-sense region of the TGB1 ORF that contains the sgRNAβ2 promoter.