Once ammonia is incorporated, it can be used to form other nitrogenous compounds. For example, glutamate can donate its amino group to oxalactate in a transaminase reaction, producing alpha-ketoglutarate and aspartate (Figure5.26c). Alternatively, glutamine can react with alpha-ketoglutarate to form two molecules of glutamate in an aminotransferase reaction (Figure5.26d). The end result of these types of reactions is the shuttling of ammonia into various carbon skeletons from which further biosynthetic reactions can occur to form all the 22 amino acids (Figure 3.12) needed to make proteins.