IDENTIFICATION OF A TRIPARTITE BASAL PROMOTER WHICH REGULATES HUMAN TERMINAL DEOXYNUCLEOTIDYL TRANSFERASE GENE-EXPRESSION

In order to locate the promoter region of the human terminal deoxynucl eotidyl transferase gene, serially truncated segments of the 5'-flanki ng region of the gene were cloned into a chloramphenicol acetyltransfe rase reporter vector. Transient transfection analyses of the terminal transferase-reporter gene constructs identified the basal promoter reg ion within -34 to +40 base pairs relative to the transcription start s ite. Three promoter elements were defined in this region. The primary element is within 34 base pairs upstream of the transcription start si te. The CAP site is 62 base pairs upstream of the translation start si te. The secondary element involves sequences around the transcription start site. The third is located 25 base pairs downstream from the ini tiation site (+25 to +40). This tripartite basal promoter was not tiss ue specific; similar patterns of promoter activity were observed in te rminal transferase expressing and non-expressing cells. Transfection a nalyses also indicated the presence of negative regulatory elements up stream of the basal promoter region, and these elements were preferent ially active in cells expressing terminal transferase.