This subsection of the ‘PTM / Processing’ section describes the position and length of an active peptide in the mature protein.
An active peptide is defined as a small polypeptide (<= 40 to 50 amino acid long) that is processed from a larger precursor protein and has a well defined biological activity on its own.
The ‘Description’ field of each ‘Peptide’ corresponds to the peptide name listed in the ‘Protein name’ subsection, under the heading “Cleaved into the following x chains:”, where ‘x’ represents the number of chains described in the ‘PTM/Processing’ section.
There can be more than one ‘Peptide’ subsection per protein entry.
Each peptide has a stable identifier.
See also the ‘Chain’ subsection that describes polypeptidic protein chains.