| tiRNAs |
5′ tiRNA |
Ribonuclease A (RNase A) or Ribonuclease T2 (RNase T2) cleave the anticodon loop of mature tRNA |
The sequence between the 5′ end of mature tRNA and the cleavage site of the anticodon loop |
| 3′ tiRNA |
The sequence between the 5′ end of mature tRNA and the cleavage site of the anticodon loop |
| tRFs |
5-tRFs |
Dicer or RNase T2 cleaves the D-loop of mature tRNA |
The sequences at the 5′ end of mature tRNA can be further classified into 5a-tRFs (approximately 15 nt), 5b-tRFs (approximately 22 nt), and 5c-tRFs (approximately 30 nt), based on their lengths. |
| 3-tRFs |
Dicer or RNase A cleaves the T-loop of mature tRNA |
The sequences at the 3′ end of mature tRNA, often including the terminal CCA sequence, can be further divided into 3a-tRFs (approximately 18 nt) and 3b-tRFs (approximately 22 nt), based on their lengths. |
| 1-tRFs |
RNase Z cleaves the 3′ tail of pre-tRNA |
These are single-stranded, ranging from 20 to 40 nt in length, with a 3′ poly-U tail, and are distributed in both the nucleus and cytoplasm. |
| 2-tRFs |
Originating from tRNAGlu, tRNAAsp, tRNAGly and pre-tRNATyr
|
There are only four types of 2-tRFs, which contain a complete anticodon arm and anticodon loop. |
| i-tRFs |
Originating from the interior of mature tRNA |
Starting from the 5′ end of mature tRNA, they encompass the anticodon loop and a portion of the D/T loop. |
