What are glycerol-3-phosphate shuttle and malate-aspartate shuttle for?

Two pathways that transport reducing equivalents from NADH into mitochondria have been characterized and are known as the glycerol-phosphate shuttle and the malate-aspartate shuttle. FIGURE 14-21. Glycerol 3-phosphate shuttle for the transport of cytoplasmic reducing equivalents to the inner mitochondrial membrane.

What does glycerol-3-phosphate shuttle do?

The glycerol-3-phosphate (G-3-P) shuttle is an important pathway for delivery of cytosolic reducing equivalents into mitochondrial oxidative phosphorylation, and plays essential physiological roles in yeast, plants, and animals. However, its role has been unclear in filamentous and pathogenic fungi.

What is the use of malate-aspartate shuttle?

The malate-aspartate (M-A) shuttle provides an important mechanism to regulate glycolysis and lactate metabolism in the heart by transferring reducing equivalents from cytosol into mitochondria.

How does the malate-aspartate shuttle system work?

Malate-Aspartate Shuttle Mammalian tissues can use a shuttle system involving malate and aspartate to transport electrons across the mitochondrial inner membrane. Oxaloacetate in the cytoplasm is converted to malate by malate dehydrogenase, oxidizing NADH to NAD.

Where does the glycerol-3 phosphate shuttle take place?

With the electron transport chain being sequestered in the inner membrane of the mitochondria, some cells have evolved a mechanism to move the electron pair, associated with the cytoplasmic pool of NAD, into the electron transport chain? SKELETAL MUSCLE & BRAIN tissues operate the glycerol-3-phosphate shuttle.

How many electrons can a glycerophosphate shuttle synthesize?

Because the electrons using the glycerophosphate shuttle enter the electron transport pathway at the level of Coenzyme Q, the electrons can only be used to synthesize a maximum of two ATP, instead of the maximum of three ATP derived from NADH formed inside the mitochondria.

How is glutamate transported in the glycerophosphate shuttle?

Oxaloacetate is regenerated in the cytosol, completing the cycle, and glutamate produced in the same reaction enters the matrix via the glutamate-aspartate transporter. When body utilises α-glycero-P-shuttle, net ATP produced by glycolysis—TCA cycle per molecule glucose oxidised will be 36 ATP (2 ATP less) and NOT 38 ATP.