Management of cellular energy by the AMP‐activated protein kinase system

The AMP-activated protein kinase is a sensor of cellular energy status that is found in all eukaryotic cells. It is activated by rising AMP and falling ATP by a complex mechanism that results in an ultrasensitive response. The functions of the different domains on the three subunits of the alphabetagamma heterotrimer are slowly being unravelled, and a recent development has been the identification of a glycogen-binding domain on the beta subunit. Along with findings that high cellular glycogen represses kinase activation, this suggests that the system may be a sensor of glycogen content as well as of AMP and ATP. New insights have been obtained into the sequence and structural features by which the kinase…