FibrinopeptideB,human is a 14-amino acid polypeptide released from the amino terminus of the fibrinogen segment.

This is amino acids 86 to 100 fragment of class II-associated invariant chain peptide called CLIP. The major histocompatibility complex class II molecule displays peptide fragments of foreign proteins to trigger a defensive reaction from the immune system. Before insertion of the foreign peptides into the binding groove, a place-holding peptide CLIP is removed. This is accomplished by the molecule DM, which is shown to increase the dissociation rate of a CLIP peptide from class II.

CCP peptide is a synthetic cyclic peptide incorporating the amino acid citrulline.