D-glyceraldehyde 3-phosphate is formed from the following three compounds in reversible reactions:
*Fructose-1,6-bisphosphate (F1,6BP), catalyzed by aldolase.
The numbering of the carbon atoms indicates the fate of the carbons according to their position in fructose 6-phosphate.
*Dihydroxyacetone phosphate (DHAP), catalyzed by triose phosphate isomerase.
*1,3-bisphosphoglycerate (1,3BPG), catalyzed by glyceraldehyde 3-phosphate dehydrogenase.