Innate immunity relies upon the ability of a variety of recognition molecules to sense pathogens through conserved molecular signatures that are often carbohydrates. Ficolins are oligomeric proteins assembled from collagen-like stalks and fibrinogen-like domains that have the ability to sense these molecular patterns on both pathogens and apoptotic cell surfaces. Three ficolins, termed L, H and M, have been identified in humans. They differ in their localization and concentration in extracellular fluids, their mode of secretion and their recognition properties. From a structural point of view, ficolins are assembled from basal trimeric subunits comprising a collagen-like triple helix and a globular domain composed of 3 fibrinogen-like domains. The globular domains are responsible for sensing danger signals whereas the collagen-like stalks provide a link with immune effectors. This review mainly focuses on the structure and recognition properties of the 3 human ficolins, as revealed by recent crystallographic analysis of their recognition domains. The ligand binding sites have been identified in the 3 ficolins and their recognition mechanisms have been characterized at the atomic level. In the case of M-ficolin, a structural transition at acidic pH disables the binding pocket, and thus likely participates in the functional cycle of this protein.
© 2009 S. Karger AG, Basel
- Carbohydrate specificity
- Innate immunity
- Pattern Recognition Receptor
- X-ray structures
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Dr. Christine Gaboriaud
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Received: February 25, 2009
Accepted after revision: May 26, 2009
Published online: August 6, 2009
Number of Print Pages : 7
Number of Figures : 3, Number of Tables : 0, Number of References : 31
Journal of Innate Immunity
Vol. 2, No. 1, Year 2010 (Cover Date: December 2009)
Journal Editor: Herwald H. (Lund), Egesten A. (Lund)
ISSN: 1662-811X (Print), eISSN: 1662-8128 (Online)
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