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Conserved structural features in glycoprotein processing glucosidase I from several tissues and species
B S Pukazhenthi1, G M Varma, I K Vijay
1Department of Animal Sciences, University of Maryland, College Park 20742.
Indian Journal of Biochemistry & Biophysics
|December 1, 1993
Summary
Glucosidase I, an enzyme crucial for glycoprotein processing, maintains a consistent 85 kDa molecular weight across various mammalian tissues. Subtle differences in its structure suggest evolutionary adaptations in enzyme processing.
Area of Science:
- Biochemistry
- Molecular Biology
- Glycobiology
Background:
- Glucosidase I initiates glycoprotein processing by removing a specific glucosyl residue from oligosaccharides.
- Previous studies identified Glucosidase I in rat and bovine mammary glands as an 85 kDa enzyme with a defined domain structure.
Purpose of the Study:
- To investigate the characteristics of Glucosidase I across diverse mammalian tissues.
- To determine the molecular weight, cross-reactivity, and structural domain conservation of Glucosidase I.
Main Methods:
- Enzyme purification from various tissues (rat, mouse, guinea pig, bovine mammary glands, sheep liver, pig kidney).
- Biochemical analyses including SDS-PAGE, trypsin digestion, ConA-binding, endo H susceptibility, and peptide mapping.
- Immunological detection using anti-rat glucosidase I antibody.
Main Results:
- Glucosidase I consistently showed an 85 kDa molecular weight and cross-reactivity with anti-rat antibody in all examined tissues.
- The enzyme is a high mannose glycoprotein with conserved domain features.
- Differential trypsin digestion patterns between pig kidney and other tissues suggest evolutionary variations in primary structure.
Conclusions:
- Glucosidase I is a highly conserved enzyme in terms of molecular weight and domain structure across mammalian species.
- Observed variations in proteolytic cleavage sites indicate evolutionary divergence in the enzyme's primary sequence.