| Namespace | sequence | Obsolete | false |
| description | A biological_region of sequence that, in the molecule, interacts selectively and non-covalently with other molecules. A region on the surface of a molecule that may interact with another molecule. When applied to polypeptides: Amino acids involved in binding or interactions. It can also apply to an amino acid bond which is represented by the positions of the two flanking amino acids. |
