... categories of introns and splicing mechanisms These consist of nuclear tRNA introns [66], archaeal introns [67], nuclear mRNA introns [68], and the group I and group II introns [69, 70] Of these introns, ... 10 (denoted as ωG) The second step is initiated by an attack by the 3’-end of the released exon on the 3’ SS, which results in ligation of the exons and release of the intron RNA Successful catalysis ... cations, especially potassium ion [120], and can adopt a variety of different folding patterns depending on the relative orientation of the strands and the position of the loops 23 Figure 1-6 The...