Characterization of the Japanese pufferfish (Takifugu rubripes) T-cell receptor at locus reveals a unique genomic organization

Polymerase chain reactions with degenerate V gene segment primers were used to isolate the putative T-cell receptor alpha -chain gene (TCRA) from Japa nese pufferfish (Takifugu rubripes). The putative TCRA chain cDNA is compos ed of an N-terminus leader peptide followed by the variable region and the constant region. The variable portion of the TCRA gene is encoded by V and J gene segments separated in the germline. As in mammals, the V-J junction sequences are GC rich and highly diversified. Amino acid residues that are required to maintain the function and structural integrity of the TCRA poly peptide, including the conserved Trp-Tyr-Lys and Tyr-Tyr-Cys motifs in the V gene segments, the Lys-Leu-X-Phe-Gly-X-Gly-Thr-X-Leu motif in the J gene segment, the three cysteine residues in the constant region and the charged residues in the transmembrane region are all preserved in the pufferfish. These conserved features suggest that the TCRA gene families in fish and ma mmals have evolved from a common ancestor.