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J Biol Chem. 2016 Jan 15;291(3):1103-14. doi: 10.1074/jbc.M115.681775. Epub 2015 Nov 24.

Characterization of Microfibrillar-associated Protein 4 (MFAP4) as a Tropoelastin- and Fibrillin-binding Protein Involved in Elastic Fiber Formation.

Author information

1
From the Department of Cancer and Inflammation Research, Institute of Molecular Medicine, Faculty of Health Sciences, University of Southern Denmark, 5000 Odense C, Denmark.
2
the Center for Biochemistry, Faculty of Medicine and.
3
the Center for Biochemistry, Faculty of Medicine and the Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany.
4
the Department of Infection, Immunity and Inflammation, and Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN, United Kingdom, and.
5
From the Department of Cancer and Inflammation Research, Institute of Molecular Medicine, Faculty of Health Sciences, University of Southern Denmark, 5000 Odense C, Denmark, the Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, 5000 Odense C, Denmark.
6
From the Department of Cancer and Inflammation Research, Institute of Molecular Medicine, Faculty of Health Sciences, University of Southern Denmark, 5000 Odense C, Denmark, glsorensen@health.sdu.dk.

Abstract

MFAP4 (microfibrillar-associated protein 4) is an extracellular glycoprotein found in elastic fibers without a clearly defined role in elastic fiber assembly. In the present study, we characterized molecular interactions between MFAP4 and elastic fiber components. We established that MFAP4 primarily assembles into trimeric and hexameric structures of homodimers. Binding analysis revealed that MFAP4 specifically binds tropoelastin and fibrillin-1 and -2, as well as the elastin cross-linking amino acid desmosine, and that it co-localizes with fibrillin-1-positive fibers in vivo. Site-directed mutagenesis disclosed residues Phe(241) and Ser(203) in MFAP4 as being crucial for type I collagen, elastin, and tropoelastin binding. Furthermore, we found that MFAP4 actively promotes tropoelastin self-assembly. In conclusion, our data identify MFAP4 as a new ligand of microfibrils and tropoelastin involved in proper elastic fiber organization.

KEYWORDS:

analytical ultracentrifugation; calcium-binding protein; elastin; fibrillin; microfibrillar-associated protein 4; site-directed mutagenesis; surface plasmon resonance (SPR)

PMID:
26601954
PMCID:
PMC4714194
DOI:
10.1074/jbc.M115.681775
[Indexed for MEDLINE]
Free PMC Article

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