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Gene Review:

QPCT - glutaminyl-peptide cyclotransferase

Bos taurus

Fischer, W.H. et al., Böckers, T.M. et al., Pohl, T. et al., Bateman, R.C., Sykes, P.A. et al., et al.

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High impact information on QPCT

By transfection of COS-7 monkey cells with a QC cDNA/pCDM8 vector construct, QC activity was expressed [1].
A glutaminyl cyclase (QC) that is probably involved in the biosynthesis of pyroglutamyl peptides such as gonadotropin-releasing hormone and thyrotropin-releasing hormone has been purified to homogeneity from bovine anterior pituitary [1].
The subcellular distribution of glutaminyl cyclase corresponded to the one of peptidylglycine alpha-amidating monooxygenase believed to catalyze C-terminal amidations during posttranslational precursor processing [2].
Glutaminyl cyclase was not observed to require ATP and could be inhibited with 1.0 M ammonium chloride, which increased the Km and decreased the Vmax value [2].
That this activity was exhibited by an enzyme, glutaminyl cyclase, was concluded from the protein character of the activity (revealed by its abolition with trypsin and heat), the Michaelis-Menten relationship between substrate concentration and conversion rate, and the substrate specificity [2].

Biological context of QPCT

An examination of the bovine tissue distribution of QC immunoreactivity, enzyme activity, and mRNA confirmed that QC was abundant in brain and pituitary by all three measures [3].
The expression of the glutaminyl cyclase (QC), an enzyme responsible for the post-translational modification of N-terminal pyroglutamyl residues of neuropeptide precursors, was examined in bovine/porcine hypothalamic and pituitary tissue by means of immunocytochemistry and in situ hybridization [4].
In this report a rapid spectrophotometric assay for cyclization of glutaminyl-peptides to pyroglutamyl-peptides by glutaminyl cyclase is described which overcomes many of these shortcomings [5].

Anatomical context of QPCT

The neurointermediate lobe was devoid of signals for QC mRNA, but showed significant QC-immunoreactivity on secretory granules of axonal nerve endings [4].

Analytical, diagnostic and therapeutic context of QPCT

A rapid fluorometric assay for N-terminal glutaminyl cyclase activity using high-performance liquid chromatography [6].

References

Primary structure and functional expression of a glutaminyl cyclase. Pohl, T., Zimmer, M., Mugele, K., Spiess, J. Proc. Natl. Acad. Sci. U.S.A. (1991) [Pubmed]
Identification of a mammalian glutaminyl cyclase converting glutaminyl into pyroglutamyl peptides. Fischer, W.H., Spiess, J. Proc. Natl. Acad. Sci. U.S.A. (1987) [Pubmed]
Evidence for tissue-specific forms of glutaminyl cyclase. Sykes, P.A., Watson, S.J., Temple, J.S., Bateman, R.C. FEBS Lett. (1999) [Pubmed]
Glutaminyl-cyclase expression in the bovine/porcine hypothalamus and pituitary. Böckers, T.M., Kreutz, M.R., Pohl, T. J. Neuroendocrinol. (1995) [Pubmed]
A spectrophotometric assay for glutaminyl-peptide cyclizing enzymes. Bateman, R.C. J. Neurosci. Methods (1989) [Pubmed]
A rapid fluorometric assay for N-terminal glutaminyl cyclase activity using high-performance liquid chromatography. Consalvo, A.P., Young, S.D., Jones, B.N., Tamburini, P.P. Anal. Biochem. (1988) [Pubmed]

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AgaP_AGAP009673	Anopheles gambiae str. PEST
QPCT	Canis lupus familiaris
qpctla	Danio rerio
qpctlb	Danio rerio
isoQC	Drosophila melanogaster
QPCT	Gallus gallus
QPCT	Homo sapiens
QPCT	Macaca mulatta
MGG_03692	Magnaporthe oryzae 70-15
Qpct	Mus musculus
NCU11249	Neurospora crassa OR74A
QPCT	Pan troglodytes
RGD1562284	Rattus norvegicus
qpct	Xenopus (Silurana) tropicalis
LOC101732244	Xenopus (Silurana) tropicalis

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