Binding of a DNA fragment containing a __NODE__ __NODE__ response element and a protein fragment ( 613 752 ) containing a LXXLL motif 1 ( aa sequence LLQLL ) and a mutant LXXLL motif 2 ( L688A L689A ) ( aa sequence LHKLL ) and a LXXLL motif 3 ( aa sequence LRYLL ) and a receptor binding domain from __NODE__ protein and a protein protein complex consisting of __NODE__ and of __NODE__ does not occur in a cell free system .