In __SP__ 1 cells , a protein chimera composed of a protein fragment containing a carboxy terminal domain from __SP__ Adra2a protein and of a mutant protein fragment ( C351G ) resistant to __SP__ Pertussis toxin protein [Pertussis_toxin] and containing a N terminal domain from __SP__ __NODE__ protein in __SP__ 1 cells causes little or no change in activation of __SP__ __NODE__ protein .