Cells make their largest decisions at a few regulatory hubs: AMPK, which senses energy; mTOR, which decides whether to grow; p53, which guards the genome; and NF-κB, which coordinates inflammation and immunity. These hubs regulate one another in a web rather than a chain of command, but they have something in common. AMPK reads the ratio of AMP and ADP to ATP directly. mTOR checks the supply of S-adenosylmethionine through a dedicated sensor. p53 carries acetyl, methyl, ubiqu

p53 is widely known as the “guardian of the genome,” and it is the single most commonly altered protein in human cancer. Yet the modern p53 molecule did not appear all at once with the rise of multicellular animals. Over more than a billion years, it evolved from a simple environmental stress sensor with an on/off switch into one of the most sophisticated information-processing molecules in living cells — a system that gathers signals from dozens of independent pathways and s

How Molecular Motion Allows Cells to Sense and Communicate About Energy Every living cell must constantly answer the fundamental question whether it has enough energy to grow, or must it conserve resources to survive? The molecule responsible for answering that question is AMPK, the AMP-activated protein kinase. AMPK acts as a cellular energy sensor and regulator that monitors energy levels by responding to changes in the ratios of AMP to ATP and ADP to ATP inside cells. At f