So ammonium must be combined with Pyruvate. Now, where do we get the Pyruvate from? Well, inside our muscle, we have glycogen storages. We break down the glycogen to glucose, and we break down glucose into Pyruvate via glycolysis. So we generate ATP. That ATP can be used by the cell, and the Pyruvate can also be used to actually combine with ammonium to form glutamate, and then glutamate is transformed into aluminium.