AMP-sensitive protein kinase (AMPK) is expressed in a variety of tissues and is activated when [AMP] is increased and [ATP] is decreased, i.e. when the energy charge in cells of the tissue is low. Examples of enzymes that are regulated by AMPK-mediated phosphorylation is Acetyl-CoA carboxylase and HMG-CoA reductase in hepatocytes, and hormone sensitive triacyl glycerol lipase (hormone sensitive lipase) in adipose tissue. One of the enzymes listed above has to be activated due to AMPK-mediated phosphorylation. Which one? Explain why it "makes sense"!
Answers
5' AMP-activated protein kinase or AMPK or 5' adenosine monophosphate-activated protein kinase is an enzyme (EC 2.7.11.31) that plays a role in cellular energy homeostasis, largely to activate glucose and fatty acid uptake and oxidation when cellular energy is low. It belongs to a highly conserved eukaryotic protein family and its orthologues are SNF1 and SnRK1 in yeast and plants, respectively. It consists of three proteins (subunits) that together make a functional enzyme, conserved from yeast to humans. It is expressed in a number of tissues, including the liver, brain, and skeletal muscle. In response to binding AMP and ADP, the net effect of AMPK activation is stimulation of hepatic fatty acid oxidation, ketogenesis, stimulation of skeletal muscle fatty acid oxidation and glucose uptake, inhibition of cholesterol synthesis, lipogenesis, and triglyceride synthesis, inhibition of adipocyte lipogenesis, activation of adipocyte lipolysis, and modulation of insulin secretion by pancreatic beta-cells.