 Further evidence for this link includes structural similarity between the U2/U6 junction of spliceosomal RNA and domain V of group II introns, which contains the catalytic AGC triad and much of the heart of the active site, as well as parity between conserved 5' and 3' end sequences.Many of these IEPs, including LtrA, share a reverse transcriptase domain and a "Domain X".Maturase K (MatK) is a protein somewhat similar to those intron-encoded proteins, found in plant chloroplasts.