An Unknown Protein Binding Specifically to the Coding Strand of the Estrogen Responsive Element.

An unknown protein, Designated ERE-C-SSBP, which binds to the single coding strand of estrogen response element (ERE) tightly and specifically, has been discovered unexpectedly during an attempt to establish an ER-ERE gel retardation assay with a 13 bp core fragment of the ERE as a probe. Some of its characteristics, such as subcellular location, tissue distribution, heat stability and relation with divalent metal ions are reported. Interestingly, it may be down-regulated by estrogen. Its value in 29 breast carcinoma samples is to some degree in reverse correlationship with that of ER. The significance of these findings is discussed.