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Rat procathepsin B. Proteolytic processing to the mature form in vitro
1Joint Diseases Laboratory, Shriners Hospital for Crippled Children, Montreal, Quebec, Canada.
The Journal of Biological Chemistry
|August 5, 1992
Summary
This study shows how rat procathepsin B is processed into its mature form. Researchers found that certain proteinases, including cathepsin B itself, can process the precursor, suggesting autocatalysis in cathepsin B maturation.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Procathepsin B is the precursor to the active enzyme cathepsin B.
- Understanding procathepsin B processing is crucial for studying its function and regulation.
Purpose of the Study:
- To investigate the processing of rat procathepsin B in yeast.
- To identify proteinases involved in procathepsin B maturation.
- To characterize the mechanism of procathepsin B activation.
Main Methods:
- Expression and purification of wild-type and mutant rat procathepsin B in yeast.
- Incubation of purified procathepsin B with various proteinases.
- Amino-terminal sequencing of processed cathepsin B forms.
Main Results:
- Yeast secretion produced both latent and mature forms of procathepsin B.
- A non-active mutant procathepsin B was secreted unprocessed.
- Cathepsins D, L, and mature cathepsin B processed the mutant precursor.
- Processing by cathepsin B and dipeptidylpeptidase I yielded correctly processed cathepsin B.
- Procathepsin B processing can be autocatalytic.
Conclusions:
- Cathepsin B maturation involves specific proteinase activities.
- The processing pathway can involve autocatalysis, particularly intermolecularly.
- Further research into cathepsin B regulation and function is warranted.