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Profibrillin-1 maturation by human dermal fibroblasts: proteolytic processing and molecular chaperones
Debra D Wallis1, Elizabeth A Putnam, Jill S Cretoiu
1Department of Internal Medicine, University of Texas-Houston Medical School, Houston, Texas 77030, USA.
Journal of Cellular Biochemistry
|October 3, 2003
Summary
Profibrillin-1 processing occurs after secretion, not intracellularly. Furin, a specific endoprotease, is identified as the enzyme responsible for this crucial proteolytic step in the secretory pathway.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Fibrillin-1 is a crucial extracellular matrix protein.
- Its precursor, profibrillin-1, requires proteolytic processing.
- The exact site and enzyme for profibrillin-1 processing have been debated.
Purpose of the Study:
- To determine if profibrillin-1 processing occurs intracellularly or post-secretion.
- To identify the specific endoprotease responsible for profibrillin-1 cleavage.
- To identify proteins interacting with profibrillin-1 during its secretion.
Main Methods:
- Blocking protein secretion using Bafilomycin A1 and low temperature (22°C).
- Immunoprecipitation to detect protein interactions.
- Using a specific furin inhibitor (alpha-1-antitrypsin, Portland variant).
Main Results:
- Profibrillin-1 processing was confirmed to occur extracellularly, not within the trans-Golgi network.
- Endoplasmic reticulum chaperones BiP and GRP94 were found to interact with profibrillin-1.
- Furin inhibition blocked profibrillin-1 processing, identifying it as the responsible enzyme.
Conclusions:
- Profibrillin-1 processing is a post-secretory event.
- Furin is the primary endoprotease responsible for cleaving profibrillin-1.
- BiP and GRP94 interact with profibrillin-1 in the secretory pathway.