CHARACTERIZATION OF A 1,8-KB DNA SEGMENT LOCATED UPSTREAM FROM THE HUMAN HA-RAS PROTOONCOGENE AND POSSIBLY REGULATING ITS FUNCTION

We have cloned a 1.8-kb segment of DNA just adjacent to the 5' end of the 6.4-kb BamHI fragment which contains the Ha-ras oncogene (ras1; Ge nBank notation HUMRASH), Electrophoretic mobility shift assays (EMSA) indicate the presence of multiple nuclear protein-binding sites within the 1.8-kb segment, At least three putative regulatory protein-bindin g sites have been identified in a 206-bp subfragment by DNase I footpr int analysis, Within the subfragment containing the DNase-protected re gions, there is also a segment containing a number of consensus sequen ces for DNA-binding proteins and two sub-sequences that exhibit strong sequence homology to at least two previously characterized enhancers, These data suggest that a novel set of regulatory elements may lie as far as 2 kb upstream from the normal Ha-ms transcription start points .