Glyceraldehyde 3-phosphate (G3P) is an intermediate in both glycolysis and gluconeogenesis. G3P is formed from the following three reversible reactions:

• Fructose-1,6-bisphosphate, catalyzed by aldolase
• Dihydroxyacetone phosphate (DHAP), catalyzed by triose phosphate isomerase (TIM)
• 1,3-bisphosphoglycerate, catalyzed by glyceraldehyde 3-phosphate dehydrogenase

This intermediate is also of some importance since this is how glycerol (as DHAP) enters the glycolytic and gluconeogenesis pathways.