Fig. 1
From: Action mechanisms and research methods of tRNA-derived small RNAs
Categorization of tRNA-derived fragments (tRFs) and tRNA halves (tiRNAs). tRFs are classified into five subclasses, i-tRF, tRF-1, tRF-2, tRF-3, and tRF-5. i-tRF, tRF-2, tRF-3, and tRF-5 are derived from mature tRNAs digested by Angiogenin (ANG), Dicer, or other RNases at different sites, while tRF-1 is derived from pre-tRNA digested by RNase Z. tiRNAs are divided into two major subtypes, 5′tiRNA and 3′tiRNA, which are derived from mature tRNAs cleaved by ANG at the anticodon ring. Fragments are longer than tiRNAs are called stress-induced tRNA-5 (sitRNA-5) or sitRNA-3
