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Primary structure and functional expression of a glutaminyl cyclase
1Department of Molecular Neuroendocrinology, Max Planck Institute for Experimental Medicine, Göttingen, Federal Republic of Germany.
Summary
Researchers purified glutaminyl cyclase (QC), an enzyme likely involved in synthesizing key hormones like gonadotropin-releasing hormone. They identified its genetic sequence and confirmed its expression in bovine brain tissue.
Area of Science:
- Biochemistry
- Molecular Biology
- Neuroendocrinology
Background:
- Glutaminyl cyclase (QC) is implicated in the biosynthesis of pyroglutamyl peptides.
- Key examples of these peptides include gonadotropin-releasing hormone (GnRH) and thyrotropin-releasing hormone (TRH).
Purpose of the Study:
- To purify and characterize glutaminyl cyclase (QC) from bovine anterior pituitary.
- To determine the primary structure of QC and identify its gene sequence.
- To confirm the functional expression and tissue distribution of QC.
Main Methods:
- Purification of glutaminyl cyclase from bovine anterior pituitary.
- N-terminal sequence analysis and isolation of a cDNA clone.
- Nucleotide sequencing to deduce protein and prepropeptide sequences.
- Transfection of COS-7 cells for functional expression analysis.
- mRNA hybridization to determine tissue-specific gene expression.
Main Results:
- Glutaminyl cyclase was purified to homogeneity.
- A 2088-base-pair cDNA clone encoding a 330-residue protein and a 31-residue prepropeptide was isolated.
- Functional QC activity was confirmed after transfection of COS-7 cells.
- QC gene expression was predominantly observed in bovine brain tissue.
Conclusions:
- The primary structure of bovine glutaminyl cyclase was determined.
- The gene encoding QC is expressed primarily in the brain.
- This study provides molecular insights into the biosynthesis of important pyroglutamyl peptides.