Figure 2.

Self-splicing products under different conditions and identification of bands. (A) B.h.I1(B) transcript was self-spliced in standard conditions of 100 mM MgCl₂, 50 mM Tris (pH 7.5) and 2 M NH₄Cl at 55°C for 15 min, or in alternative conditions with substitutions of 10 mM MgCl₂ or 10 mM MnCl₂ for 100 mM MgCl₂, or 0.5, 1.0 or 2 M NaCl for 2 M NH₄Cl. RNA size markers are indicated to the left in nucleotides, and product identifications to the right are explained in the text. (B) Time course of the self-splicing reaction under standard conditions, illustrating the initial formation of linear intron and ligated exons, and subsequent accumulation of other products. (C) Sequences and structures of the RNA cleavages produced in the self-splicing reaction. Arrows indicate cleavage sites at: the exon–intron junction of B.h. I1(B); the ICP cleavages at −107, −99 and −81 relative to the 3′ end of the intron; and the ICP cleavage at +68 relative to the 5′ end of the intron. EBS1 pairings of the intron are shown above the exon sequences.