Demonstration of promoter function for the 5'-flanking region of the human gene for terminal deoxynucleotidyl transferase.

Promoter activity was detected by transfection of pBS vectors that carried the 5'-flanking region of the gene for human terminal deoxy-nucleotidyltransferase (TdT) and the entire human TdT cDNA into COS7 monkey kidney cells, with direct assay of the expressed enzymatically active TdT. The synthesis of TdT was also detected immunologically using polyclonal rabbit antibodies against bovine TdT. One fifth of the TdT activity detected in normal thymocytes was detected in transfected COS7 cells. This results suggests that a lymphoid-specific regulatory system is present in B or T-cells to promote the effective expression of TdT.