D-glyceraldehyde 3-phosphate + NADP(+) + phosphate = (2R)-3-phospho-glyceroyl phosphate + H(+) + NADPH Tetramer of either four A chains (GAPDH 2) or two A and two B chains (GAPDH 1). Belongs to the glyceraldehyde-3-phosphate dehydrogenase family.