Base triples conserved in four 23S rRNA structures. (A) Triples from domains I (red), II (green) and III (blue) highlighted in spacefilling mode and numbered using the H. marismortui numbering unless stated otherwise. (B) Triples in domain IV (red), domain V (green) and domain VI (blue). Triples not originally detected in the H. marismortui structure which were detected in the T. thermophilus search and were found to have conserved equivalent interactions in the other three structures are also highlighted in section (A) as orange spacefills for domain I and cyan spacefills for domain II, and in section (B) as magenta spacefills for domain V and cyan spacefills for domain VI. (C, D) A stacked triples motif located on a junction in domain V which joins three subdomains in four of the available structures compared. (E) shows the two stacked triples, separated for clarity, consist of two planar UAU Hoogsteen, Watson Crick triples. The colors used for each of the 23S subunits compared are presented in section (F).