QPCT
QPCT (glutaminyl-peptide cyclotransferase, also known as QC or GCT) is a secreted enzyme that catalyses the formation of pyroglutamyl residues at the N-terminus of peptides. It is the human pituitary glutaminyl cyclase and belongs to the glutaminyl-peptide cyclotransferase family. Browse Assay Genie's current range of QPCT research reagents below, or read on for the biology behind the target.
QPCT is responsible for the biosynthesis of pyroglutamyl peptides. The enzyme acts on peptides carrying an N-terminal glutaminyl residue and converts it to pyroglutamate, a modification it also catalyses more generally as N-terminal pyroglutamate formation. Substrate preference has been characterised: QPCT shows a bias against acidic and tryptophan residues adjacent to the N-terminal glutaminyl residue, and chain length beyond the second residue is of little importance.
The QPCT gene encodes human pituitary glutaminyl cyclase, which accounts for the pyroglutamyl residues found in many neuroendocrine peptides. The human amino acid sequence is 86% identical to that of bovine glutaminyl cyclase, and the mouse ortholog is Qpct. UniProt lists the protein as secreted. HGNC places it in the M28 metallopeptidases group and in the glutaminyl-peptide cyclotransferase family.
QPCT is also of interest in amyloid research. In vitro, it catalyses pyroglutamate formation on the N-terminally truncated amyloid-beta peptide [Glu-3]-amyloid-beta, derived from APP, and it may be involved in forming N-terminal pyroglutamate on several amyloid-related, plaque-forming peptides. Researchers studying this enzyme often work with a QPCT antibody, a QPCT ELISA kit or recombinant QPCT protein to examine its expression and activity. A related protein, QPCTL, shares the family relationship.
QPCT is responsible for the pyroglutamyl residues present in many neuroendocrine peptides, making it central to studies of their maturation.
In vitro, QPCT catalyses pyroglutamate formation on [Glu-3]-amyloid-beta, a truncated form of APP-derived amyloid-beta peptides.
QPCT may contribute to N-terminal pyroglutamate formation on several amyloid-related, plaque-forming peptides, a question relevant to neurodegeneration research.
QPCT disfavours acidic and tryptophan residues next to the N-terminal glutamine, making it a useful model for cyclotransferase specificity.
QPCT is responsible for the biosynthesis of pyroglutamyl peptides. It converts N-terminal glutaminyl residues to pyroglutamate. In vitro it acts on [Glu-3]-amyloid-beta, and it may be involved in modifying several amyloid-related, plaque-forming peptides.
QPCT is the HGNC symbol for glutaminyl-peptide cyclotransferase. Aliases are QC and GCT, and the protein is also described as human pituitary glutaminyl cyclase. Its enzyme classification is EC 2.3.2.5. It is distinct from the related gene QPCTL.
Yes. The human enzyme is 86% identical in amino acid sequence to bovine glutaminyl cyclase, and the mouse ortholog is Qpct. Check the datasheet of any product for its validated reactivity.
A related glutaminyl-peptide cyclotransferase family member with a page at Assay Genie.
Gene and protein annotations from HGNC, NCBI Gene and UniProt Q16769; product specifications from Assay Genie datasheets.