Binding of a DNA fragment containing a TRE 2 ( 5 ' AGGTCAGGGTCA 3 ' from mutant __NODE__ gene ( G?A G?A G?A with its TRE 2 ( 5 ' AGGTCAGGGTCA 3 ' mutated ) DNA endogenous promoter and heterodimer consisting of __SP__ __NODE__ and of __SP__ __NODE__ does not occur in a cell free system .