Entity
| Chain ID | Description | Type | Chain length | Formula weight | Number of molecules | DB Name (Accession) | Biological source | Descriptive keywords |
| A | Ferritin, middle subunit | polymer | 176 | 20599.1 | 1 | Lithobates catesbeiana (American bullfrog) | Ferritin M,Ferritin H',Ferritin X | |
| FE (II) ION | non-polymer | 55.8 | 6 | |||||
| MAGNESIUM ION | non-polymer | 24.3 | 7 | |||||
| CHLORIDE ION | non-polymer | 35.5 | 9 | |||||
| water | water | 18.0 | 361 |
