DNA replication origin and transcriptional enhancer in c-myc gene share the c-myc protein binding sequences

We have previously reported that c-myc protein, or protein(s) complexed with c-myc protein, binds to the region upstream of the first exon of the c-myc gene and that this region contains an origin of cellular DNA replication (ori) and also a transcriptional enhancer. Here we show by Southwestern blotting that c-myc protein binds directly to a 7 bp sequence within the above region. Furthermore, we show that the c-myc protein binding sequences are indispensable for both ori and enhancer functions, but that additional sequences are required for maximal ori and enhancer activities. Thus, c-myc protein is a sequence specific factor which is apparently used both in initiation of DNA replication and in regulation of RNA transcription.