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EMBO J. 1998 Mar 16;17(6):1688-99.

Dual regulation of the AMP-activated protein kinase provides a novel mechanism for the control of creatine kinase in skeletal muscle.

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MRC Molecular Medicine, Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital, DuCane Road, London W12 0NN.


The AMP-activated protein kinase (AMPK) is activated by a fall in the ATP:AMP ratio within the cell in response to metabolic stresses. Once activated, it phosphorylates and inhibits key enzymes in energy-consuming biosynthetic pathways, thereby conserving cellular ATP. The creatine kinase-phosphocreatine system plays a key role in the control of ATP levels in tissues that have a high and rapidly fluctuating energy requirement. In this study, we provide direct evidence that these two energy-regulating systems are linked in skeletal muscle. We show that the AMPK inhibits creatine kinase by phosphorylation in vitro and in differentiated muscle cells. AMPK is itself regulated by a novel mechanism involving phosphocreatine, creatine and pH. Our findings provide an explanation for the high expression, yet apparently low activity, of AMPK in skeletal muscle, and reveal a potential mechanism for the co-ordinated regulation of energy metabolism in this tissue. Previous evidence suggests that AMPK activates fatty acid oxidation, which provides a source of ATP, following continued muscle contraction. The novel regulation of AMPK described here provides a mechanism by which energy supply can meet energy demand following the utilization of the immediate energy reserve provided by the creatine kinase-phosphocreatine system.

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