In the urea cycle, the carbon skeleton of aspartate is preserved as:

Fumerate

Urea cycle is located in the cytosol of the liver cells and matrix of mitochondria. Urea is a non-toxic compound that is transported via the bloodstream to the kidney where it is excreted with the urine. The enzyme aspartate aminotransferase catalyze transamination between glutamate and oxaloacetate, resulting aspartate enters urea cycle.