T-hairpin structure found in the RNA element involved in piRNA biogenesis

Structural comparison between the T-hairpin of Tj-cis RNA and similar structures. (A) The T-hairpin of Tj-cis RNA. The minimized averaged structure (middle) and a superposition with yeast tRNA^Phe (PDB ID: 6TNA) (right) are shown. T-loop of the tRNA was colored in magenta and, G18 and G19 of D-arm were colored in tan. (B) Yeast tRNA^Phe (PDB ID: 6TNA). (C) E. coli 23S rRNA (5J7L). (D) Cobalamin riboswitch (4FRG). (E) FMN Riboswitch (4YCO). For each panel, the schematic drawing of the 7(6)-nt loop structure with the closing G–C base pair is shown. Positions in the 7-nt loop are indicated by italics.