Key enzyme in glycolysis that catalyzes the first step of the pathway by converting D-glyceraldehyde 3-phosphate (G3P) into 3-phospho-D-glyceroyl phosphate. Essential for the maintenance of cellular ATP levels and carbohydrate metabolism (By similarity). D-glyceraldehyde 3-phosphate + NAD(+) + phosphate = (2R)-3-phospho-glyceroyl phosphate + H(+) + NADH Carbohydrate degradation; glycolysis; pyruvate from D-glyceraldehyde 3-phosphate: step 1/5. Homotetramer. Plants contain two types of GAPDH: cytosolic forms which participate in glycolysis and chloroplast forms which participate in photosynthesis. All the forms are encoded by distinct genes. Belongs to the glyceraldehyde-3-phosphate dehydrogenase family.