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Fibrillin assembly: dimer formation mediated by amino-terminal sequences
J L Ashworth1, V Kelly, R Wilson
1Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, University of Manchester, Oxford Road, Manchester, M13 9PT, UK. cay.kielty@man.ac.uk
Journal of Cell Science
|October 3, 1999
Summary
Researchers studied fibrillin-1 and fibrillin-2 molecules, finding both can form extracellular dimers. Differences in dimer stability were observed, suggesting proline- and glycine-rich regions are key to fibrillin assembly into microfibrils.
Area of Science:
- Biochemistry
- Molecular Biology
- Extracellular Matrix
Background:
- Fibrillins are essential components of the extracellular matrix, forming microfibrils.
- Understanding fibrillin assembly is crucial for comprehending connective tissue disorders.
Purpose of the Study:
- To investigate the role of proline- and glycine-rich regions in fibrillin-1 and fibrillin-2 assembly.
- To determine if these regions mediate specific molecular recognition events during fibrillin microfibril formation.
Main Methods:
- Recombinant expression of fibrillin-1 (profib-1) and fibrillin-2 (glyfib-2) molecules.
- SDS-PAGE, size fractionation, chemical crosslinking, and co-immunoprecipitation.
- In vitro translation systems and proteinase K digestion.
Main Results:
- Both profib-1 and glyfib-2 formed extracellular dimers, with glyfib-2 exhibiting both disulfide-bonded and non-covalent associations.
- Dimerization was cell-independent and not solely an intracellular event.
- Molecular chaperones including BiP, protein disulfide isomerase, and calreticulin associated with recombinant fibrillins.
Conclusions:
- Extracellular dimer formation, mediated by proline- and glycine-rich regions, is a critical initial step in fibrillin microfibril assembly.
- Subtle differences in dimer stability between fibrillin isoforms may relate to variations in proline- and glycine-rich sequences.
- Chaperone interactions suggest a role in regulating fibrillin assembly and preventing premature dimerization.