Table 1.
Comparison of 5'- and 3'-editing reactions.
| 5'-Editing | 3'-Editing | ||
|---|---|---|---|
| Similarities | Locations | mitochondria and chloroplast in eukaryotes | |
| Mechanism | nucleotide removal and transfer | ||
| Usage | restore base pairs, make functional tRNAs | ||
| Differences | Enzyme | 3'-5'-polymerases (Thg1-like proteins, or TLPs) and unknown enzymes | unknown enzymes, possibly similar to TRAMP complex |
| Nucleotidyl transfer reaction | 3'-5': template-dependent | 5'-3': both template-independent and template-dependent | |
| Substrates | mismatch-containing tRNAs | Overlapping tRNAs and some mismatch-containing tRNAs | |