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Immunogenetics. 2005 Aug;57(7):535-48. Epub 2005 Sep 29.

Characterization of a C3-like cDNA in a coral: phylogenetic implications.

Author information

1
Department of Biological Sciences, Florida International University, University Park Campus, 11200 SW 8th Street, Miami, FL 33199, USA.

Abstract

C3, C4, and C5 are thiolester-containing proteins (TEPs) of vertebrate complement. The identification of the molecular origin of the TEP family, and more specifically the ancestor protein of complement components C3, C4, and C5, remains a fundamental question. The prevailing paradigm suggests that duplication and divergence of these proteins occurred after the deuterostome split in phylogeny. It is believed that the ancestor of thiolester-containing complement proteins was alpha-2-macroglobulin (A2M)-like, a noncomplement-related protein. Here we describe a C3-like cDNA from a gorgonian coral, Swiftia exserta. This study provides evidence for the origins of a complement-related C3-like gene in the Precambrian period, predating both protostomes and deuterostomes. Furthermore, one may speculate that complement-like opsonic reactions were evolving at the earliest stages of metazoan evolution. This calls for a reassessment of the present concepts concerning the origins and evolution of TEPs.

PMID:
16041540
DOI:
10.1007/s00251-005-0005-1
[Indexed for MEDLINE]

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