The function of ENSG00000115828 (QPCT, glutaminyl-peptide cyclotransferase) is as follows. Responsible for the biosynthesis of pyroglutamyl peptides. Has a bias against acidic and tryptophan residues adjacent to the N- terminal glutaminyl residue and a lack of importance of chain length after the second residue. Also catalyzes N-terminal pyroglutamate formation. In vitro, catalyzes pyroglutamate formation of N-terminally truncated form of APP amyloid-beta peptides [Glu-3]-amyloid-beta. May be involved in the N-terminal pyroglutamate formation of several amyloid-related plaque-forming peptides. {ECO:0000269|PubMed:15063747, ECO:0000269|PubMed:18486145, ECO:0000269|PubMed:21288892}.