First genomic sequence of the human T-cell receptor δ2 gene (TRDV2)

The genomic sequence of the human V62 (TRDV2) gene is reported. One clone, ALY67W2, was isolated from the LY67 library [1] by screening with a 250 bp Hind 111-Pvu I fragment containing the 5' region of the cDNA XI3 clone [2] and shown to contain the TRDV2 gene. Comparison of the sequence of the genomic TRDV2 gene with those of four V2 cDNAs [2,3] confirms that, in the human TRD locus, like in the TRG one [4], there is no somatic mutation and the variability of the delta chains depends from the combinatorial diversity of the V, D and J gene segments and from the presence of N regions. Hence, the germline V2 sequence, reported here, will allow to assess this Nregion diversity in the cells which rearrange functionally and express the TRDV2 gene. Moreover, it will help in defining the contribution of the different D segments. By southern blot analysis, the genomic TRDV2 probe, clone pDV2SP0.5, a 500 bp Sma I-Pst I fragment isolated from ALY67V62 and subcloned in pUC18, detects a unique band with Eco RI (12.5 kb), Hind III (4.0 kb) and Xba I (3.6 kb) digests showing that the TRDV2 gene is the single member of its subgroup.