This peptide sequence is found in residues 25 to 33 of the mouse self/tumor antigen glycoprotein (mgp100). This fragment is a H-2Db–restricted epitope recognized by CD8+ T cells. Mgp100 is an enzyme normally involved in pigment synthesis, and the epitope fragment is typically expressed in both normal melanocytes and melanoma cells.
Pyroglutamyl (pGlu) peptides may spontaneously form when either Glutamine (Q) or Glutamic acid (E) is located at the sequence N-terminus. The conversion of Q or E to pGlu is a natural occurrence and in general it is believed that the hydrophobic γ-lactam ring of pGlu may play a role in peptide stability against gastrointestinal proteases. Pyroglutamyl peptides are therefore considered a normal subset of such peptides and are included as part of the peptide purity during HPLC analysis.