In __SP__ , binding of a protein fragment ( 91 408 ) containing a __NODE__ zipper domain 2 3 from __SP__ __NODE__ protein and mutant __SP__ __NODE__ protein ( N terminal truncation 1 9 ) is greater than binding of a mutant protein fragment ( 91 408 ) ( L147A L148A with its __NODE__ zipper domain 2 mutated ) containing a __NODE__ zipper domain 2 3 from __SP__ __NODE__ protein and mutant __SP__ __NODE__ protein ( N terminal truncation 1 9 ) .