D-glyceraldehyde 3-phosphate + NADP(+) + phosphate = (2R)-3-phospho-glyceroyl phosphate + H(+) + NADPH Carbohydrate biosynthesis; Calvin cycle. Tetramer of either four A chains (GAPDH 2) or two A and two B chains (GAPDH 1). 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.