Figure 1.

Overview of identified RNA fragments derived from tRNA transcripts. Various stable RNA molecules originate from mature tRNA [5’ and 3’ tRNA halves, 5’ and 3’ tRNA-derived fragments (tRFs)] and pre-tRNA transcript [3’external transcribed spacer (3’ETS) or 3’ trailer]. The 5’ and 3’ tRNA halves derive from both 5’ and 3’ sides of mature tRNA after cleavage at the close vicinity of the anticodon. The 5’ and 3’ tRFs originate from cleavage in the D-loop and T-loop, respectively. Recent findings describe internal transcribed spacers (ITS) as putative functional RNA molecules; however, there is still no evidence of free stable ITS in the cell.