Figure 3.

Processing of histone insertion mutant pre-mRNAs in the presence of length suppressor U7 RNAs. (A) Partial sequences of histone insertion substitution mutants and U7 RNA length suppressor mutants. The 5C insertion in the histone pre-mRNA is indicated by block letters while further base substitutions in this substrate are listed below. The point of insertion into U7 RNA is marked, with the inserted residues in blocked residues and the Sm site shaded. (B) In lanes 1–4, histone pre-mRNAs HDEpu→py, wild-type, 5C, and 10C were injected into untreated oocytes. The same histone pre-mRNAs were injected into depleted oocytes rescued with the following material. Lanes: 5–8, in vitro-transcribed U7wt RNA; 9–12, U75bp RNA; 13–16, U75nobp RNA; 17–20, U710 RNA; 21–24, not rescued.