Figure 7.

Possible pathways of formate production in higher plants. Reactions shown are: 1, FDH; 2, methanol oxidase; 3, formaldehyde dehydrogenase; 4, S-formyl hydrolase; 5, SHMT; 6, sarcosine dehydrogenase; 7, Gly decarboxylase; 8, 5,10-methylene-THF dehydrogenase; 9, 5,10-methenyl-THF cyclohydrolase; 10, 10-formyl-THF synthetase; 11, glycollate oxidase; 12, oxalate decarboxylase; 13, pyruvate dehydrogenase; 14, alcohol dehydrogenase; 15, malate synthase; 16, isocitrate lyase; 17, pyruvate formate lyase. Reactions 2, 3, 4, 12, and 14 are cytosolic; reactions 1 and 7 are mitochondrial; reactions 11, 15, and 16 are peroxisomal; reactions 6, 8, and 9 have been described in both cytosol and mitochondria; reactions 5 and 13 are both plastidial and mitochondrial; and reaction 17 has only been described in microorganisms and mitochondria from unicellular algae.