And so what this enzyme does is it takes this product of reaction one and it transfers this carbon group kicking off the orthophosphate, it transfers this group onto ornathine to form citrulline. So this is what ornithine looks like. And ultimately this group here, minus this oxygen and this phosphate group is transported onto this nitrogen of the ornathine to form the citrulline. 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.