Figure 6. The role of the malate-aspartate shuttle in NADH regeneration. The malate/aspartate shuttle appears to compensate for the lack of glycerol-3-phosphate shuttling. NADH is transported into the mitochondrion by the interconversion of malate and aspartate via oxaloacetate in the cytoplasm and the mitochondrion and involves cytoplasmic and mitochondrial glutamate and 2-oxoglutarate and isoenzymes of aspartate aminotransferase. The net redox effect of the malate-aspartate shuttle is that NADH in the cytosol is oxidized to NAD⁺, and NAD⁺ in the matrix is reduced to NADH. AAT, aspartate aminotransferase; GK, glucokinase; GLUT, glucose transporter; G3PDH, glyceraldehyde-3-phosphate dehydrogenase; MDH, malate dehydrogenase; 2OG, 2-oxoglutarate; OGC, 2-oxoglutarate carrier; PPP, pentose phosphate pathway.