At the cellular level, as a virus invades, its DNA or RNA trigger immune responses in the healthy host cells. How this process is triggered and a better understanding of the specific enzymes involved is still being defined. A collaboration across multiple X-ray facilities, including the Berkeley Center for Structural Biology beamlines at the Advanced Light Source (ALS), compared the enzymes involved in both human and insect immune responses. They used protein crystallography to closely examine the structures, and learned that although overall function is similar, each group of organisms has a slightly different DNA-binding surface and resulting molecular immune response.