Figure 6.

Intramolecular labeling pattern of the Calvin–Benson cycle. Summing the labeling resulting from three different pentose phosphate sources shows that one of the Ru5Ps will have carbon 1 and 2 labeled from carbon 3 of DHAP, carbon 3 of RuBP of all Ru5Ps will have a label from carbon 1 of GAP and carbons 4 and 5 should have no label after one occurrence of the pentose phosphate reactions of the Calvin–Benson cycle. DHAP = dihydroxyacetone phosphate, E4P = erythrose 4-phosphate, F6P = fructose 6-phosphate, GAP = glyceraldehyde 3-phosphate, R5P = ribose 5-phosphate, Ru5P = ribulose 5-phosphate, S7P = sedoheptulose 7-phosphate and Xu5P = xylulose 5-phosphate.