The promoter regions of the T-cell receptor V9 gamma (TRGV9) and V2 delta (TRDV2) genes display short direct repeats but no TATA box.

T lymphocytes expressing the T-cell gamma delta receptor have been shown to express preferentially the T-cell receptor V9 gamma (TRGV9) gene, in association with the T-cell receptor V2 delta (TRDV2) gene. In this paper, we report that the promoter regions of the TRDV2 and TRGV9 genes, which are preferentially expressed early in T-cell differentiation, display short direct repeats but no TATA box, in contrast to the V gamma genes belonging to subgroup I. The TCCTCAGT octanucleotide found 100 pb upstream of the ATG of the HD-Mar V alpha transcript, a TCR V alpha gene without a TATA box, is observed upstream of TRDV2 but not TRGV9. Of interest is the presence of a characteristic decanucleotide AGGTGGT(T)GAG in the promoter regions of both the TRDV2 and TRGV9 genes.