| Architecture | Description | Class | n° Families | Structure |
|---|---|---|---|---|
| SRP | Signal recognition RNAs | structured_complex | 8 | |
| Intron_gpI-like | RNAs structured similarly to Group I introns | structured_complex | 5 | |
| U4_snRNA | U4 spliceosomal small nuclear RNAs | structured_complex | 3 | |
| U1_snRNA | U1 spliceosomal small nuclear RNAs | structured_complex | 4 | |
| complex unclassified | Complex RNAs with no known distinct domain | structured_complex | 277 | |
| RNaseP | Ribonuclease P structures | structured_complex | 7 | |
| IRES_multi_domain | RNAs with Internal Ribosome Entry Sites and other domains | structured_complex | 28 | |
| multiple_domains | RNAs with multiple and/or various domains | structured_complex | 22 | |
| Intron_gpII-like | RNAs structured similarly to Group II introns | structured_complex | 12 | |
| telomerase | Telomerase RNA components | structured_complex | 4 | |
| rRNA | Ribosomal RNAs | structured_complex | 14 |