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. Also acts as a regulator of cellular polarity by remodeling the actin cytoskeleton; probably by indirectly activating myosin. Regulates lipid synthesis by phosphorylating and inactivating lipid metabolic enzymes such as ACACA, ACACB, GYS1, HMGCR and LIPE; regulates fatty acid and cholesterol synthesis by phosphorylating acetyl-CoA carboxylase (ACACA and ACACB) and hormone-sensitive lipase (LIPE) enzymes, respectively. Regulates insulin-signaling and glycolysis by phosphorylating IRS1, PFKFB2 and PFKFB3. AMPK stimulates glucose uptake in muscle by increasing the translocation of the glucose transporter SLC2A4/GLUT4 to the plasma membrane, possibly by mediating phosphorylation of TBC1D4/AS160. Regulates transcription and chromatin structure by phosphorylating transcription regulators involved in energy metabolism such as CRTC2/TORC2, FOXO3, histone H2B, HDAC5, MEF2C, MLXIPL/ChREBP, EP300, HNF4A, p53/TP53, SREBF1, SREBF2 and PPARGC1A. Acts as a key regulator of glucose homeostasis in liver by phosphorylating CRTC2/TORC2, leading to CRTC2/TORC2 sequestration in the cytoplasm. In response to stress, phosphorylates 'Ser-36' of histone H2B (H2BS36ph), leading to promote transcription. Acts as a key regulator of cell growth and proliferation by phosphorylating TSC2, RPTOR and ATG1/ULK1: in response to nutrient limitation, negatively regulates the mTORC1 complex by phosphorylating RPTOR component of the mTORC1 complex and by phosphorylating and activating TSC2. In response to nutrient limitation, promotes autophagy by phosphorylating and activating ATG1/ULK1. In that process also activates WDR45. In response to nutrient limitation, phosphorylates transcription factor FOXO3 promoting FOXO3 mitochondrial import. AMPK also acts as a regulator of circadian rhythm by mediating phosphorylation of CRY1, leading to destabilize it. May regulate the Wnt signaling pathway by phosphorylating CTNNB1, leading to stabilize it. Also has tau-protein kinase activity: in response to amyloid beta A4 protein (APP) exposure, activated by CAMKK2, leading to phosphorylation of MAPT/TAU; however the relevance of such data remains unclear in vivo. Also phosphorylates CFTR, EEF2K, KLC1, NOS3 and SLC12A1. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. SNF1 subfamily. 2 alternatively spliced human isoforms have been reported. Note: This description may include information from UniProtKB.
Protein type: AMPK subfamily; Autophagy; CAMK group; CAMKL family; EC 188.8.131.52; EC 184.108.40.206; EC 220.127.116.11; EC 18.104.22.168; Kinase, protein; Protein kinase, CAMK; Protein kinase, Ser/Thr (non-receptor)
Molecular Function: [acetyl-CoA carboxylase] kinase activity; [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity; AMP-activated protein kinase activity; ATP binding; cAMP-dependent protein kinase activity; chromatin binding; histone serine kinase activity; metal ion binding; protein binding; protein C-terminus binding; protein kinase activity; tau protein binding; tau-protein kinase activity
Biological Process: activation of MAPK activity; CAMKK-AMPK signaling cascade; cell cycle arrest; cellular response to calcium ion; cellular response to ethanol; cellular response to glucose starvation; cellular response to glucose stimulus; cellular response to hydrogen peroxide; cellular response to hypoxia; cellular response to nutrient levels; cellular response to organonitrogen compound; cellular response to oxidative stress; cellular response to prostaglandin E stimulus; cholesterol biosynthetic process; cold acclimation; energy homeostasis; fatty acid biosynthetic process; fatty acid homeostasis; fatty acid oxidation; glucose homeostasis; glucose metabolic process; histone-serine phosphorylation; lipid biosynthetic process; macroautophagy; motor behavior; negative regulation of apoptotic process; negative regulation of gene expression; negative regulation of glucosylceramide biosynthetic process; negative regulation of insulin receptor signaling pathway; negative regulation of lipid catabolic process; negative regulation of TOR signaling; negative regulation of tubulin deacetylation; neuron cellular homeostasis; positive regulation of autophagy; positive regulation of cell proliferation; positive regulation of cellular protein localization; positive regulation of cholesterol biosynthetic process; positive regulation of gene expression; positive regulation of glycolytic process; positive regulation of mitochondrial transcription; positive regulation of peptidyl-lysine acetylation; positive regulation of protein targeting to mitochondrion; positive regulation of skeletal muscle tissue development; protein heterooligomerization; protein phosphorylation; regulation of circadian rhythm; regulation of macroautophagy; regulation of microtubule cytoskeleton organization; regulation of peptidyl-serine phosphorylation; regulation of signal transduction by p53 class mediator; regulation of stress granule assembly; regulation of vesicle-mediated transport; response to activity; response to caffeine; response to camptothecin; response to gamma radiation; response to hypoxia; response to UV; rhythmic process; signal transduction; Wnt signaling pathway