Sp1 specific binding sites within the human H-ras promoter: potential role of the 6 bp deletion sequence in the T24 H-ras1 gene.

: Transcriptionally active domains have been identified and located within the 5'-region of the human normal and mutant T24 H-ras1 promoters, and have been characterised by linkage to the coding sequences of the bacterial chloramphenicol acetyltransferase (CAT) gene or by using DNaseI foot-printing analysis of the promoter sequence. It has been shown, using the latter method, that Sp-1 transcription factor binds to six GC sequences within the H-ras promoter. In the present study we have used unfractionated nuclear protein preparations from HeLa cells and a gel retardation assay to analyse specific binding of nuclear protein preparations from HeLa cells and a gel retardation assay to analyse specific binding of nuclear factors to several oligonucleotide sequences of the human H-ras1 promoter. Our data demonstrate the presence of three Spl specific binding sequences in the T24 promoter, one of them containing a Sp-1 consensus GGCGGC absent in the normal H-rasl promoter.