Background：

Catalytic subunit of AMP-activated protein kinase (AMPK)， an energy sensor protein kinase that plays a key role in regulating cellular energy metabolism. In response to reduction of intracellular ATP levels， AMPK activates energy-producing pathways and inhibits energy-consuming processes: inhibits protein， carbohydrate and lipid biosynthesis， as well as cell growth and proliferation. AMPK acts via direct phosphorylation of metabolic enzymes， and by longer-term effects via phosphorylation of transcription regulators.