IDENTIFICATION AND ANALYSIS OF THE CHICKEN CD3-EPSILON GENE

The chicken T cell receptor CD3 epsilon gene was isolated using a dege nerate polymerase chain reaction. The 1883 bp long cDNA encoded a tran smembrane protein of 16.9 kDa lacking N-linked glycosylation sites. Co mparison of the chicken and mammalian CD3 epsilon proteins revealed lo w homology in the extracellular domain with clusters of similarities l ocated around the N-terminal cysteine residue and proximal to the tran smembrane region. The high conservation of the cytoplasmic domain incl uded motifs important for signal transduction. The alignment of all CD 3 gamma, CD3 delta and CD3 epsilon proteins allowed the identification of highly conserved residues and motifs. Southern blot analysis indic ated the presence of a single copy CD3 epsilon gene. The expression of the CD3 epsilon transcript was limited to T cells and natural killer cells. A recessive mutation of the CD3 epsilon gene in the CB chicken strain enabled the mapping of the epitope recognized by the CT3 monocl onal antibody. This analysis of the first non-mammalian CD3 epsilon ge ne provides novel information about evolutionary conserved structural features and its expression in natural killer cells.