In a system of purified components , the affinity of binding of __SP__ __NODE__ protein and mutant __SP__ __NODE__ protein ( N150H K154T Q319L M354I ) is the same as the affinity of binding of mutant __SP__ __NODE__ protein ( K68N P69Q L70Q L73Q L74Q ) and mutant __SP__ __NODE__ protein ( N150H K154T Q319L M354I ) .