Metabolic Pathways
Mechanisms of energy sensing, glucose handling, lipid transport, and cellular growth.
Energy Sensing
Deep inside every cell, an enzyme called AMPK works as a fuel gauge. It reads the ratio of spent to charged energy molecules and switches on when reserves run low. An upstream kinase called LKB1 activates it, and AMPK throttles the costly business of building new molecules. It flips the cell toward burning fat and recycling worn-out parts, while directly opposing a competing growth pathway called mTOR. A rising AMP signal alone boosts the enzyme catalytic speed up to 10-fold, an amplification loop that scales with how severe the shortage is. This circuit explains why exercise, fasting, and the diabetes drug metformin all converge on one target. In animal studies, boosting it has extended lifespan by up to 20 percent. This gauge tends to grow unresponsive with age, a change considered a hallmark of metabolic aging, and keeping it responsive through activity and fasting supports healthspan.
One-Carbon Metabolism
The one-carbon metabolism pathway encompasses the folate cycle and methionine cycle, providing methyl groups for DNA methylation and other critical processes.