Cloning and Sequence Analysis of Porcine CD8α Full-length cDNA

The porcine CD8α full-length cDNA was amplified and cloned from total RNA of lymphocytes by RT-PCR and RACE(rapid amplification of cDNA ends). Sequence analysis indicated that the porcine CD8α full-length cDNA was 2179 nt in length, including 165nt of 5′untranslated region, 711 nt of open reading frame and 1303 nt of 3′untranslated region(GenBank accession number 517855). The open reading frame encoded a protein precursor with 236 amino acids residues and one N-glycosylation site. Seven cysteine residues (Cys46, Cys57, Cys118, Cys167, Cys182, Cys216 and Cys218) were conserved among mammalian species, which were associated with formation of Ig-alike domain,αα homodimer or αβ heterodimer, and an highly conserved protein tyrosine kinase p56lck recognition site CKCP was in the cytoplasmic domain. The comparison of the deduced amino acids sequence of porcine CD8α with those of human, cattle, mouse, dog and cat showed that the amino acids homology were 55.7%, 57.6%, 35.6%, 56.8% and 56.4 %, respectively.