a non-catalytic subunit of AMPK, a conserved kinase of the CAMKL family. AMPK is an energy-sensing protein that plays a key role in regulating cellular energy homeostasis. Environmental stress, such as heat shock, nutrient deprivation, hypoxia and ischemia, indirectly activate AMPK by the depletion of cellular ATP and the concomitant rise of ADP and AMP levels. Allosteric activation is achieved primarily by rising ADP levels, and not solely by AMP levels as previously thought. 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. Also acts as a regulator of cellular polarity by remodeling the actin cytoskeleton, probably by indirectly activating myosin. AMPK is a heterotrimer of an alpha catalytic subunit (AMPKA1 or -2), a beta (AMPKB1 or -2) and a gamma non-catalytic subunit (AMPKG1, -2 or -3). Different possible combinations of subunits give rise to 12 different holoenzymes. Beta subunits act as scaffolds on which the AMPK complex assembles, via its C-terminus that bridges alpha and gamma subunits. AMPK-beta1 or -beta2 subunits are required for assembling of AMPK heterotrimers and are important for regulating enzyme activity and cellular localization. AMPK beta1beta2 null mouse muscles reveal an essential role for AMPK in maintaining mitochondrial content and glucose uptake during exercise. Phosphorylation by ULK1 and ULK2 inhibits AMPK activity. Note: This description may include information from UniProtKB.
Protein type: Autophagy; Protein kinase, regulatory subunit