A novel chimeric Ig heavy chain from a teleost fish shares similarities to IgD
AUTOR(ES)
Wilson, Melanie
FONTE
The National Academy of Sciences of the USA
RESUMO
IgD is considered to be a recently evolved Ig, being previously found only in primates and rodents. Here we describe, from a teleost fish (the channel catfish, Ictalurus punctatus), a novel complex chimeric Ig heavy chain, homologous, in part, to the heavy chain (δ) of IgD. In addition to alternative secretory or membrane-associated C termini, this chimeric molecule contains a rearranged variable domain, the first constant domain of μ, and seven constant domains encoded by a δ gene homolog. Identification of the catfish gene as δ is based on the following properties: sequence relatedness to mammalian δ; a location within the IgH locus that is immediately downstream of the μ gene; separate terminal exons for the secretory and membrane forms; coexpression with the complete μ chain in some but not all B cells. These results (i) suggest that IgD is an ancient immunoglobulin that was present in vertebrates ancestral to both the mammals and the ray-finned fishes, and (ii) raise the possibility that this Ig isotype may have served an as yet unidentified important function early in the evolution of the immune system.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=20768Documentos Relacionados
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