The 3-flanking region of the mouse c-fos gene contains a cluster of GGTCA hormone response-like elements.

We previously identified an estrogen response element in the 3'-flanking region of the c-fos protooncogene [1, 2]. This element, GGTCAnnnCAGCC, has one half-site identical to that of the consensus ERE (GGTCAnnnTGACC) but only limited homology to the second half-site. Because of this non-canonical sequence and atypical location in the 3'-untranslated region of an estrogen target gene, we decided to analyze sequences adjacent to this element for the possible presence of other regulatory elements. We now report that the 635 base pairs downstream of the c-fos ERE contain: (i) an unusual cluster of 7 GGTCA hormone response-like elements; (ii) potential binding sites for other known DNA binding proteins; and (iii) a sequence specific binding site for a non-estrogen receptor protein present in hormone target tissues.