This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of carbohydrate, Subject name: Biochemistry
Reducing equivalents produced in glycolysis are transpoed from cytosol to mitochondria by 
Select and explain. 
A. Carnitine, B. Creatine, C. Malate shuttle, D. Glutamate shuttle
C: Malate shuttle
Answer: C: Malate shuttle 
Explanation: Malate-Aspaate Shuttle Mitochondrial membrane is impermeable to NADH. The NADH equivalents generated in glycolysis are therefore to be transpoed from the cytoplasm to mitochondria for oxidation. This is achieved by malate-aspaate shuttle or malate shuttle, which operates mainly in the liver, kidney, and hea. The cycle is operated with the help of enzymes malate dehydrogenase (MDH) and aspaate aminotransferase. From one molecule of NADH in the mitochondria, 2 1/2 ATP molecules are generated.Ref: DM Vasudevan, 7th edition, page no: 260