Involved in plastidial glycolytic pathway and plays a specific role in glycolytic energy production in non-green plastids and chloroplasts. Essential for breakdown of starch to form sucrose for export to non-photosynthetic tissues, and to generate primary metabolites for anabolic pathways such as fatty acid and amino acid synthesis. Plays an important role in plant development by providing substrates for the phosphorylated pathway of serine biosynthesis in roots. Plays a crucial role in pollen development. Functionally redundant with GAPCP1. D-glyceraldehyde 3-phosphate + NAD(+) + phosphate = (2R)-3-phospho-glyceroyl phosphate + H(+) + NADH Homotetramer. Expressed in shoot and root vasculature, leaf veins and vascular tissue of flowers and siliques. No visible phenotype under normal growth conditions. Gapcp1 and gapcp2 double mutants have severe dwarf phenotypes with arrested root development and male sterility. Pollen grains show shrunken and collapsed forms and cannot germinate. Belongs to the glyceraldehyde-3-phosphate dehydrogenase family.