Glyceraldehyde 3-phosphate dehydrogenase is an enzyme that catalyzes the sixth step of glycolysis and thus serves to break down glucose for energy and carbon molecules. In addition to this long established metabolic function, GAPDH has recently been implicated in several non-metabolic processes, including transcription activation, initiation of apoptosis , and ER to Golgi vesicle shuttling. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) catalyses the conversion of glyceraldehyde 3-phosphate as the name indicates. This is the 6th step of the breakdown of glucose (glycolysis), an important pathway of energy and carbon molecule supply located in the cytosol of eukaryotic cells. Glyceraldehyde 3-phosphate is converted to D-glycerate 1,3-bisphosphate in two coupled steps.