Another thing, though, is we have to regenerate that original catalytic residue because remember, enzymes are always regenerated after the reaction. We cannot actually use up our enzymes. And so in step three, what happens? This phosphorhistidine basically swings over to another site within our enzyme, and that site contains a GDP. And now in step four, the GTP receives the orthophosphate from this histidine residue to basically form that GTP and also regenerate that original catalytic histidine residue that is found in the active side of the enzyme. So we see that in this process.