Staying in Charge

Science's STKE  27 Mar 2007:
Vol. 2007, Issue 379, pp. tw109
DOI: 10.1126/stke.3792007tw109

Under normal conditions, the intracellular concentration of adenosine triphosphate (ATP) is on the order of 1 millimolar. Numerous enzymes and regulatory proteins rely on this universal currency of energy for anabolic, catabolic, and general housekeeping processes. One of the primary enzymes that regulates ATP levels is the AMP-activated protein kinase (AMPK), which senses the relative ratio of ATP to AMP. When this ratio falls, AMPK phosphorylates metabolic enzymes, which then consume less ATP and make more of it. Townley and Shapiro have solved the structure of the fission yeast AMPK homolog and demonstrate the competitive binding of ATP and AMP at a single nucleotide site, where the absence of counterions appears to amplify the discrimination between the mono- and triphosphate ligands.

R. Townley, L. Shapiro, Crystal structures of the adenylate sensor from fission yeast AMP-activated protein kinase. Science 315, 1726-1729 (2007). [Abstract] [Full Text]

D. G. Hardie, Balancing cellular energy. Science 315, 1671-1672 (2007). [Summary] [Full Text]