5'-AMP-activated protein kinase catalytic subunit alpha-1 (AMPK alpha-1) is responsible for the regulation of fatty acid synthesis by phosphorylation of acetyl-CoA carbo, Xenopus/Amphibian,ylase. AMPK alpha-1 also regulates cholesterol synthesis via phosphorylation and inactivation of hormone-sensitive lipase and hydro, Xenopus/Amphibian,ymethylglutaryl-CoA reductase. AMPK alpha-1 acts as a metabolic stress-sensing protein kinase that switches off biosynthetic pathways when cellular ATP levels are depleted and when 5'-AMP rises in response to fuel limitation and/or hypo, Xenopus/Amphibian,ia.