Cg-I kappa B, a new member of the I kappa B protein family characterized in the pacific oyster Crassostrea gigas

Inhibitors of NF-kappa B (I kappa Bs) have been implicated as major components of the Rel/NF-kappa B signaling pathway, which is an important mediator of immune responses throughout much of the animal kingdom. Here we report the first characterization of a bivalve mollusc cDNA that encodes a novel I kappa B member called Cg-I kappa B showing the conservation of most I kappa B protein characteristics. Sequences as well as phylogenetic analyses reveal a high level of identity between not only Cg-I kappa B and other mollusc and insect I kappa B-like proteins but also similarities to vertebrate I kappa B-alpha and -epsilon isoforms. Expression analyses demonstrated that the transcript is widely expressed in all oyster tissues. This work is consistent with our previous discovery of several members of an NF-kappa B pathway in Crassostrea gigas and further sustains the hypothesis of a conserved scheme of immune gene regulation through most of the metazoans. (c) 2007 Elsevier Ltd. All rights reserved.