AMP-activated protein kinase catalytic subunit alpha (AMPKα)

AMP‐activated protein kinase catalytic subunit alpha is the enzymatic core of a heterotrimeric serine/threonine protein kinase complex known as AMP‐activated protein kinase (AMPK)—a master regulator of cellular energy homeostasis. The full holoenzyme consists of one catalytic α, one regulatory β, and one nucleotide-sensing γ subunit; each exists in multiple isoforms encoded by distinct genes (PRKAA1, PRKAA2, PRKAB1, PRKAB2, PRKAG1, PRKAG2, PRKAG3) allowing tissue-specific combinations. The enzyme senses increases in intracellular AMP/ADP relative to ATP during metabolic stress. Upon activation—primarily via phosphorylation at threonine‐172—the complex shifts metabolism toward ATP-generating catabolic pathways while suppressing biosynthetic/anabolic processes that consume ATP. It directly phosphorylates numerous substrates involved in lipid/glucose metabolism, autophagy, cell growth regulation, and more. Because dysregulation contributes to diseases like type II diabetes mellitus, obesity, cancer progression/metastasis, neurodegeneration, and cardiovascular disorders—and because it mediates some therapeutic effects of drugs like metformin—AMPK is considered an important therapeutic target across several indications.

Other names

5'-AMP-activated protein kinase catalytic subunit alphaProtein kinase, AMP-activated, alpha 1 (for the α1 isoform)PRKAA1 (gene encoding α1 isoform)PRKAA2 (gene encoding α2 isoform)AMPKalphaAMPKA2 (for the α2 isoform)

Allosteric activation via increased AMP/ADP binding to γ subunit under energy stress conditions leading to phosphorylation at Thr172 on the α subunit by upstream kinases such as LKB1 or CaMKKβ/CaMKKII. Indirect activation through inhibition of mitochondrial electron transport chain or glycolysis causing increased cellular AMP/ATP ratio. Direct binding to allosteric sites on the enzyme complex by synthetic activators.