In a cell free system , binding of a DNA fragment ( 72 43 ) containing a __NODE__ response element from __SP__ __NODE__ gene(s) and heterodimer consisting of frog __NODE__ and of __SP__ __NODE__ is greater than binding of a DNA fragment ( 72 43 ) containing a __NODE__ response element from __SP__ __NODE__ gene(s) and heterodimer consisting of frog __NODE__ and of __SP__ __NODE__ .