*3.1.2 tRF*

tRFs are shorter transcripts of 14–30 nts that are produced by cleavage of tRNA at the D-loop, T-loop or stem region by Ang, Dicer and another yet to be identified member of the RNase superfamily [57]. Cleavage of tRNA at the D-loop generates fragments of three different lengths—tRF-5a (14–16 nts), tRF-5b (22–24 nts) or tRF-5c (28–30 nts). Similarly, cleavage at the T-loop produces tRF-3a (18 nt) or tRF-3b (22 nt). The cleavage of pre-tRNA at the 3′ end results in the generation of tRF-1 (**Figure 1B**) [57, 58].
