In a cell free system , binding of a DNA fragment ( 456 427 ) containing a __NODE__ response element from __SP__ __NODE__ gene and heterodimer consisting of frog __NODE__ and of __SP__ __NODE__ is greater than binding of a DNA fragment ( 456 427 ) containing a __NODE__ response element from __SP__ __NODE__ gene and heterodimer consisting of frog __NODE__ and of __SP__ __NODE__ .