Figure 2.

Generic Biosynthetic Pathways of Poly(β-L-Malic acids) (PMLAs) in Eukaryotic Cells.

Glucose is transported into the cytoplasm where it is metabolized by glycolysis to produce pyruvate (green). Excess CO₂ activates the reductive extramitochondrial pathway to generate malate (blue). When exogenous carbonates are absent, intramitochondrial malate formation via the oxidative pathway takes place in the mitochondrial matrix through either the tricarboxylic acid (TCA) cycle or the glyoxylate shunt (orange). Through either pathway, malates are polymerized to form PMLA in the cytoplasm (gray). A PMLA synthetase has been proposed that possibly combines the activities of a malyl-AMP ligase and an unknown PMLA polymerase, in conjunction with an auxiliary peptide or enzyme (e.g., spherulin 3b in P. polycephalum) [30,39].