 AIR + CO2 → CAIR + 2H+

The seventh is catalyzed by phosphoribosylaminoimidazolesuccinocarboxamide synthase.CAIR + L-Aspartate + ATP → SAICAR + ADP + Pi

The eight is catalyzed by adenylosuccinate lyase.SAICAR → AICAR + Fumarate

The products AICAR and fumarate move on to two different pathways.