Figure 4.

The strength of the 3'ss competes with Rev responsiveness. (A) Nucleotide sequence of one-intron constructs with mutations in the 3'ss A5. The reported branch point sequences for A5 (grey boxes, asterix indicates the branch point nucleotide), the 3'ss A4c, a, b, A5 (black boxes) and the PPT (hatched) are marked. Mutated nucleotides compared to the wild type are underlined. (B) Northern blot analyses of the p(A)⁺ RNA after transient transfection of HeLa-T4⁺ cells with one-intron constructs carrying SA5 mutations (cf. Fig.2). (C) Diagram of the hGH standardized relative amounts of spliced (left) and unspliced (right) transcripts from (B). The maximal amount was defined as 100%. The numbers below correspond to the lanes of the Northern blot.