The peptide sequence ERMRPRKRQGSVRRRV corresponds to pseudosubstrate region of the e-isotype of protein kinase C (PKCe) with an alanine to serine substitution. PKCe exhibits an apparent specificity for the native peptide (Km = 68 mM).
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.