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10:17
Pulse-chase Analysis of N-linked Sugar Chains from Glycoproteins in Mammalian Cells
Published on: April 27, 2010
Differences in glycosylation pattern of human secretory ribonucleases
J J Beintema1, A Blank, G L Schieven
1Biochemisch Laboratorium, Rijksuniversiteit Groningen, The Netherlands.
The Biochemical Journal
|October 15, 1988
Summary
Researchers isolated and sequenced human urine ribonuclease (RNase HUA), a glycoprotein differing from pancreatic RNase. Structural variations in secretory RNases likely stem from organ-specific modifications.
Area of Science:
- Biochemistry
- Molecular Biology
- Proteomics
Background:
- Secretory ribonuclease (RNase) enzymes play diverse biological roles.
- Human urine contains a major secretory RNase (RNase HUA) whose structure and origin are not fully elucidated.
Purpose of the Study:
- To isolate and characterize the major secretory ribonuclease (RNase) from human urine.
- To compare the structure of urinary RNase with other human secretory RNases, such as pancreatic and seminal RNases.
Main Methods:
- Isolation and sequencing of RNase HUA using automatic Edman degradation.
- Peptide and glycopeptide analysis.
- SDS/polyacrylamide-gel electrophoresis and activity staining to confirm enzyme purity.
Main Results:
- RNase HUA is a glycoprotein of 128 amino acids, with an additional C-terminal threonine compared to pancreatic RNase.
- All three potential glycosylation sites (Asn-34, Asn-76, Asn-88) are occupied by complex-type oligosaccharide chains.
- Glycosylation at Asn-88 is a novel finding in mammalian secretory RNases.
- Urinary and seminal RNases share structural similarities, including C-terminal threonine.
Conclusions:
- Structural differences among human pancreatic, urinary, and seminal RNases arise from organ-specific post-translational modifications.
- RNase HUA represents a distinct secretory RNase isoform with unique glycosylation patterns.
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