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Procathepsin D cannot autoactivate to cathepsin D at acid pH
L B Larsen1, A Boisen, T E Petersen
1Department of Molecular Biology, University of Aarhus, Denmark.
FEBS Letters
|March 15, 1993
Summary
Bovine procathepsin D undergoes limited processing at acidic pH, forming pseudocathepsin D. Autoproteolysis alone cannot generate the mature lysosomal cathepsin D form.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Cathepsin D is a key aspartic protease involved in protein degradation.
- The maturation pathway of cathepsin D involves proteolytic processing of its pro-form.
Purpose of the Study:
- To determine the amino acid sequence of the propart of bovine procathepsin D.
- To investigate the proteolytic processing and activation of bovine procathepsin D in vitro.
Main Methods:
- Protein sequencing
- SDS-PAGE analysis
- In vitro incubation at varying pH and time
Main Results:
- Procathepsin D processing at acidic pH (3.5-5.0) yields pseudocathepsin D via cleavage between LeuP26 and IleP27.
- Extended incubation results in further processing, but mature cathepsin D is not formed.
- Autoproteolysis alone is insufficient for generating mature lysosomal cathepsin D.
Conclusions:
- Bovine procathepsin D undergoes specific proteolytic cleavage to form pseudocathepsin D.
- The complete maturation to lysosomal cathepsin D likely requires additional factors or cellular compartments.
- Understanding this processing is crucial for studying lysosomal enzyme function and related pathologies.