ATPsynthase is an amazing protein. Our cells use these generators to produce energy. It is pretty much what allows us to become the big hulking mass of cells we are today. Some bacteria also have this protein, but it is used for propulsion.

From what I understand all DNA is 90% compatible because most of that is useless or very basic functions like cellular division and energy generation.

Well, the mitochondria in our cells are descended from bacteria and retain their bacteria-style genes and proteins.