Isolation, sequence and expression of a cDNA encoding the α-chain of the feline CD8.

We have cloned, sequenced and expressed a cDNA encoding the α-chain of feline CD8. This clone, named FT8-10, has an open reading frame with 720 nucleotides in length encoding a protein with 239 amino acid residues. Sequence analysis has revealed that the feline CD8 α-chain (CD8α) shares significant homology with human (T8/Leu-2), bovine (BoCD8), rat (MRC OX8) and mouse (Lyt-2) CD8α subunits. Cysteine residues as well as the tyrosine kinase p56^kk binding site are well conserved. Besides, no putative N-linked glycosylation site was found. Interestingly, immunofluorescence analysis of COS-7 cells transfected with feline CD8α expression plasmid driven by SRα promoter showed that the expressed feline CD8α cross-reacted with an anti-human CD8α monoclonal antibody OKT8, but did not react with an anti-feline monoclonal antibody, FT-2, which is thought to recognize the feline analogue of the human T8/Leu-2 and murine Lyt-2 molecules expressed on cytotoxic/suppressor T cells. [ABSTRACT FROM AUTHOR]