The preceding step, also differing from normal glycolysis, involves the conversion of fructose 1-phosphate to dihydroxyacetone phosphate and glyceraldehyde, essentially splitting a six-carbon sugar into two three-carbon sugars. The normal glycolytic reaction involves an additional phosphate on the glyceraldehyde (i.e., glyceraldehyde 3-phosphate, from fructose 1,6-bisphosphate). Thus, the liver pathway must phosphorylate the triose. Triose kinase catalyzes this step using ATP.
The following step in the pathway is the standard glycolytic step, catalyzed by triose phosphate isomerase.