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The creatine phosphate shuttle is an intracellular energy shuttle which facilitates transport of high energy phosphate from muscle cell mitochondria to myofibrils. This is part of the Phosphocreatine metabolism. In mitochondria, ATP levels are very high as a result of glycolysis, TCA cycle, oxidative phosphorylation processes,whereas creatine phosphate levels are low. This makes conversion of creatine to phosphocreatine a highly favored reaction. Phosphocreatine, is a very-high-energy compound. Phosphocreatine, then diffuses from mitochondria to myofibrils. In myofibrils, during exercise (contraction) ADP levels are very high, which favors resynthesis of ATP. Thus phosphocreatine breakdown to creatine giving its inorganic phosphate for ATP formation. Creatine returns to mitochondria for resynthesis of creatine phosphate. The popularity of creatine as a dietary supplement for athletes, to increase muscle strength, suggests that the biosynthesis of creatine itself may be a limiting factor in operating this intracellular energy shuttle. In some vertebrates, Arginine phosphate plays a similar role. == References == *''Biochemistry'', 3rd edition, Mathews, van Holde & Ahern. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「creatine phosphate shuttle」の詳細全文を読む スポンサード リンク
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