Int. J. Mol. Sci. 2010, 11, 407-426; doi:10.3390/ijms11020407 OPEN ACCESS International Journal of Molecular Sciences ISSN 1422-0067 www.mdpi.com/journal/ijms Review The Fibrillar Collagen Family Jean-Yves Exposito *, Ulrich Valcourt, Caroline Cluzel and Claire Lethias Institut de Biologie et Chimie des Protéines, IFR 128 Biosciences Lyon-Gerland, CNRS UMR 5086, Université de Lyon, 7 passage du Vercors, F-69367 Lyon Cedex 07, France; E-Mails:
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[email protected] (C.L.) * Author to whom correspondence should be addressed; E-Mail:
[email protected]; Tel.: +33-4-72-72-26-77; Fax: +33-4-72-72-26-04. Received: 30 December 2009; in revised form: 22 January 2010 / Accepted: 23 January 2010 / Published: 28 January 2010 Abstract: Collagens, or more precisely collagen-based extracellular matrices, are often considered as a metazoan hallmark. Among the collagens, fibrillar collagens are present from sponges to humans, and are involved in the formation of the well-known striated fibrils. In this review we discuss the different steps in the evolution of this protein family, from the formation of an ancestral fibrillar collagen gene to the formation of different clades. Genomic data from the choanoflagellate (sister group of Metazoa) Monosiga brevicollis, and from diploblast animals, have suggested that the formation of an ancestral chain occurred before the metazoan radiation. Phylogenetic studies have suggested an early emergence of the three clades that were first described in mammals. Hence the duplication events leading to the formation of the A, B and C clades occurred before the eumetazoan radiation.