- A: alpha arrays
- X: Alpha-helical domain in eukaryotic DNA topoisomerase I, N-terminal DNA-binding fragment
- H: Alpha-helical domain in eukaryotic DNA topoisomerase I, N-terminal DNA-binding fragment
- T: Alpha-helical domain in eukaryotic DNA topoisomerase I, N-terminal DNA-binding fragment
- F: Topoisom_I_N