The complete cDNA and deduced amino acid sequence of equine IgE.

Abstract The cDNA from a transcript encoding the complete heavy chain of the equine immunoglobulin IgE has been cloned and sequenced. A fragment of the equine epsilon gene was amplified from cDNA using PCR and this fragment was then used to probe a horse cDNA library prepared from peripheral blood lymphocytes. A recombinant clone containing the cDNA encoding the complete horse epsilon chain and its associated V-D-J and leader, was subsequently isolated and sequenced. Comparison of the deduced amino acid sequence of equine IgE with the Cϵ heavy chains of other species indicates it to be most similar to human Cϵ (54%), followed by sheep Cϵ (52%); the greatest sequence similarity was found in the Cϵ3 and Cϵ4 domains among the species compared. The associated V-region had greatest similarity in FR1 to those reported for sheep and the cow (>80%) but less than 60% to the V H sequences of other species in FR3.