A flux map of the principal reactions involved in companion cells during the light phase. Arrow thickness indicates reaction flux value. The key on the right explains the colours used to indicate the production/consumption of key metabolites. The reactions shown are 1, GAP-3–PGA shuttle; 2, (NADP) GAP dehydrogenase; 3, 3-PGA kinase; 4, malate dehydrogenase; 5, GAP–Pi shuttle; 6, DHAP–Pi shuttle; 7, FBP aldolase; 8, FBP phosphotransferase; 9, Glu6P isomerase; 10, Glu6P dehydrogenase; 11, 6-phosphogluconolactonase; 12, gluconate-6-phosphate dehydrogenase; 13, Ru5P epimerase; 14, X5P–phosphate shuttle; 15, ribose-5-phosphate isomerase; 16, 3-PGA dehydrogenase; 17, triosephosphate isomerase; 18, transketolase; 19, H⁺-pyrophosphatase; 20, malate–oxaloacetic acid shuttle; 21, ATP–AMP shuttle; 22, plastidial ATP synthase; 23, fructose kinase; 25, mitochondrial ATP synthase; 26, adenylate kinase; 30, transaldolase; 31, pyruvate orthophosphate dikinase; 32, transketolase; 33, pyruvate channel; 34, phosphoenol pyruvate channel; and 35, plastidial ATP synthase. The metabolites shown are GAP, glyceraldehyde-3-phosphate; DPGA, 3-phospho-d-glyceroyl phosphate; 3-PGA, 3-phosphoglycerate; DHAP, Dihydroxy acetone phosphate; MAL, malate; OAA, oxaloacetic acid; Glu1P, glucose-1-phosphate; Glu6P, glucose-6-phosphate; d-6PGL, 6-phosphoglucono-∂-lactone; 6-PGA, 6-phosphogluconate; Ru5P, ribulose-5-phosphate; X5P, xylulose-5-phosphate; and Ri5P, ribose-5-phosphate.