A mechanism for the indirect transfer of photosynthetically reduced nicotinamide adenine dinucleotide phosphate from chloroplasts to the cytoplasm.

A triose phosphate/3-phosphoglycerate shuttle for the indirect transfer of photosynthetically reduced NADP from chloroplasts to the cytoplasm has been demonstrated in vitro. Triose phosphate, formed from 3-phosphoglycerate in the chloroplast, was oxidized back to 3-phosphoglycerate outside the chloroplast by the nonreversible d-glyceraldehyde 3-phosphate dehydrogenase reaction which is specific for NADP. The 3-phosphoglycerate could presumably return to the chloroplast to complete the shuttle. The properties of nonreversible d-glyceraldehyde 3-phosphate dehydrogenase are considered particularly suitable for effective operation of this shuttle system.