In this study, the sequences of several cellular genes (c-myc, c-fos, c-sis, c-mos, and the genes for urokinase, heat shock proteins, interleukin-2 and its receptor), thought to be controlled by negative regulatory factors, were examined. As a result of this comparison, multiple (and often clustered) copies of a 12 basepair (bp) element were identified in the flanking regions of these genes. Moreover, sequences with close homology to this 12 bp element were identified in specific control regions of some DNA and RNA tumor viruses. A consensus sequence (TTG nnn TTTTTT) was derived from an analysis of 111 of these elements. These sequence homologies have yielded a coherent first hypothesis, namely that this 12 bp element is the binding site of a transcriptional repressor protein.

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