Molecular cloning and phylogenetic analysis of a cDNA encoding the cat (Felis domesticus) Ig epsilon constant region

A feline splenic cDNA library was screened with a P-32-labelled cDNA probe encoding the canine IgE epsilon heavy chain subunit. A cDNA sequence of 161 4 nucleotides encoding the complete feline IgE heavy chain, as well as a po rtion of a variable region, was identified. A search of the GenBank databas e revealed an identity of 82% at the nucleotide level and 76% at the amino acid level between the feline epsilon heavy chain sequence and the canine h omologue. In a separate study, feline genomic DNA, isolated from whole feli ne embryo cells, was subjected to PCR amplification using primers based on known partial genomic DNA sequences for the feline CE gene. Following remov al of an intron from the 683 bp PCR product, the coding sequence yielded an ORF of 506 bp. The DNA sequence of this PCR clone differed by a single nuc leotide from the cDNA clone. This difference is silent, and therefore the p roteins encoded by the two sequences are identical over the regions cloned and sequenced. Phylogenetic analysis of the constant regions of nine immuno globulin epsilon genes revealed that the feline cDNA is most similar to the canine homologue. (C) 2000 Elsevier Science B.V. All rights reserved.