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Molecular structure, processing, and tissue distribution of matrilin-4.
A R Klatt1, D P Nitsche, B Kobbe
1Institute for Biochemistry and the Center for Molecular Medicine Cologne Service Laboratory, Medical Faculty, University of Cologne, Joseph-Stelzmann-Strasse 52, D-50931 Cologne, Germany.
The Journal of Biological Chemistry
|March 30, 2001
Summary
Matrilin-4, an extracellular matrix protein, forms trimers and undergoes in vivo proteolytic processing. It is broadly expressed in embryonic and adult tissues, suggesting diverse connective tissue functions.
Area of Science:
- Biochemistry
- Molecular Biology
- Extracellular Matrix Biology
Background:
- Matrilin-4 is a recently identified member of the matrilin protein family.
- Matrilins are extracellular matrix adapter proteins containing von Willebrand factor A-like domains.
Purpose of the Study:
- To biochemically characterize full-length matrilin-4.
- To investigate the oligomeric state and processing of matrilin-4.
- To determine the expression pattern and localization of matrilin-4.
Main Methods:
- Recombinant expression of full-length matrilin-4 in 293-EBNA cells.
- Purification using affinity tags.
- Biochemical characterization including electron microscopy, SDS-PAGE, mass spectrometry, and immunoblotting.
- Immunohistochemical analysis using affinity-purified antibodies.
Main Results:
- Recombinant matrilin-4 forms trimers as its largest oligomeric state.
- Proteolytic cleavage occurs in matrilin-4, generating fragments and smaller oligomers.
- Similar degradation products are observed in vivo in calvaria extracts.
- Matrilin-4 is broadly expressed in embryonic tissues (from day 7.5 post-coitum) and adult connective tissues, nervous systems, bone, and cartilage.
- In cell culture, matrilin-4 forms a filamentous network in the extracellular matrix.
Conclusions:
- Matrilin-4 exists as trimers and undergoes proteolytic processing both in vitro and in vivo.
- The broad expression pattern suggests significant roles for matrilin-4 in various connective tissues and developmental processes.
- Matrilin-4 contributes to the structural organization of the extracellular matrix.