CHARACTERIZATION OF THE CD3-GAMMA AND CD3-DELTA INVARIANT SUBUNITS OF THE SHEEP T-CELL ANTIGEN RECEPTOR

The CD3 γ and δ chains of the sheep T cell antigen receptor have been characterized by cDNA cloning. In comparison to human and mouse protein sequences, short oligopeptide stretches have been deleted from both the γ and δ chains. However, apart from further variability in the number and position of potential N‐linked glycosylation sites, the general structure of the CD3 γ and δ proteins is markedly conserved. Particularly remarkable are two motifs consisting of 8 and 32 amino acids, respectively, which locate in the C‐terminal half of each protein and which have been precisely conserved in both the CD3 γ and δ chains of all three species. These motifs probably contribute structural properties essential for the function of the CD3/T cell receptor complex. mRNA of the sheep CD3 γ (1.5 and 1.2 kb) and CD3 δ (1.5 kb) chains are transcribed from closely linked, single‐copy genes, suggesting that common mechanisms for the regulation of CD3 genes are also preserved between species. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim