And then the citrulline moves into the cytoplasm of the cell. So that's where we go to step three. So in step three now, we want to add the second amino group and that comes from Aspartate. So this is aspartate here. Ultimately we want to transfer this group here. And so the enzyme argininosuxnate synthetase, it uses an ATP, it hydrolyzed that ATP to form amp and Pyrophosphate.