α, β, γ, and δ T Cell Antigen Receptor Genes Arose Early in Vertebrate Phylogeny

AbstractA series of products were amplified using a PCR strategy based on short minimally degenerate primers and R. eglanteria (clearnose skate) spleen cDNA as template. These products were used as probes to select corresponding cDNAs from a spleen cDNA library. The cDNA sequences exhibit significant identity with prototypic α, β, γ, and δ T cell antigen receptor (TCR) genes. Characterization of cDNAs reveals extensive variable region diversity, putative diversity segments, and varying degrees of junctional diversification. This demonstrates expression of both α/β and γ/δ TCR genes at an early level of vertebrate phylogeny and indicates that the three major known classes of rearranging antigen receptors were present in the common ancestor of the present-day jawed vertebrates