AMP-activated protein kinase (AMPK) was originally discovered as 3-hydroxy 3-methylglutaryl CoA reductase (HMG-CoA reductase, HMGR) and acetyl-CoA carboxylase (ACC) inhibitor.
It stimulates various activities within cells caused by ever-changing cellular energy charge. AMPK’s key role is to regulate the energy charge of cells, hence sustaining energy homeostasis.
A recent study showed that AMPK movement can be controlled through physiological stimuli that are self-sufficient of cellular energy charge – including nutrients and hormones. But how does it improve fatty acid synthesis?
What Is Fatty Acid Synthesis?
Fatty acid synthesis uses NADPH and acetyl-CoA to create fatty acids through enzyme activities called fatty acid synthases. The process occurs inside a cell’s cytoplasm that converts acetyl-CoA into fatty acids from carbohydrates through glycolytic pathway.
The purpose of glycolytic pathway is to produce glycerol where 3 fatty acids can fuse in order to create triglycerides or triacylglycerols. It distinguishes triglycerides from fats as a result of lipogenic process.
However, when 2 fatty acids fuse with glycerol while the alcohol group is phosphorylated with phosphatidylcholine, the end product is called phospholipid.
Basically, phospholipids create bulky layers of lipid to form cell membranes. It then surrounds organelles inside the cell including mitochondria, Golgi apparatus, endoplasmic reticulum, and cell nucleus among others.
Fatty Acid Synthesis Explained Further
The end products of glycolytic are essential in converting carbohydrates into fatty acids. In humans, fatty acid synthesis usually takes place in adipose tissues and liver. But during lactation, fatty acid synthesis occurs in the mammary glands.
With the help of glycolysis, pyruvate is produced that essentially serves as intermediary in converting carbohydrates into cholesterol and fats. It takes place by means of converting pyruvate into acetyl CoA in the mitochondria.
But before that, the acetyl CoA requires to be carried in the cytosol in order to successfully synthesize cholesterol and fatty acids. Hence, the process doesn’t occur directly.
For cytosolic acetyl CoA to be obtained, citrate should be eliminated from the cycle of citric acid. If it does, cytosolic acetyl CoA is then transported into the internal membrane of the mitochondria until it reaches the cytosol.
As the process continues, the cytosolic acetyl CoA cleaves with ATP citrate lyase to produce oxaloacetate and acetyl CoA. The oxaloacetate is important in gluconeogenesis which occurs in the liver.
Otherwise, it is returned in the mitochondria to produce malate. The acetyl CoA carboxylases will then carboxylate the cytosolic acetyl CoA to create malonyl CoA. And this is the primary committed step in fatty acid synthesis.
The AMPK in the human body consist of trimeric enzyme produced by catalytic “a” subunit as well as