What is Phosphorylation?

Phosphorylation is a chemical process of adding a phosphate group to an organic compound.

Phosphorylation is essential for the functioning of proteins. Because this leads to various activities of modification in several enzymes and in turn regulating their functions.


Protein is categorized as post-translational modification. It is an enzymatic modification that takes place after or during protein biosynthesis. Most types of post-translational modification is a result or consequences of oxidative stress. One of its examples is carbonylation. Post-translational that occurs in sites are those that possess a functional group which serves as a nucleophile in a reaction.

Glucose Phosphorylation

Catabolism is the initial step of phosphorylation of sugars. It occurs when a cell allows accumulation of sugar. It plays a vital role in a sugar mechanisms. Before metabolism, the first step is the conversion of sugar into glucose.

 D-glucose + ATP -> D-glucose-6-phosphate + ADP ΔG°

The above reaction illustrates the conversion of D-Glucose to D-glucose 6-phosphate.

Importance of glucose 6-phosphate in Glycogen Synthase

  • There will be a rise in intracellular levels of glucose, 6 phosphate in fat, skeletal muscle, and liver due to a high concentration of blood glucose. In adipocytes and glucose, there would be very less effect on glycogen synthase. Whereas synthesis of glucose is directly corresponding to the concentration of blood glucose and the negative delta G value determines the point of blood sugar level within. That is why liver plays a central role in regulating blood sugar concentration by breaking down glucose into glycogen and carbon-dioxide.
  • The phosphorylation of glucose can be intensified by binding fructose-6-phosphate and can be reduced by binding fructose-1-phosphate  When fructose is consumed in the diet, there will be the conversion of fructose -1-phosphate in the liver. This initiates the action of fructose-6-phosphate in a liver.
  • Phosphorylating glucose is essential for insulin-dependent mechanisms. Excess consumption of glucose may result in impaired functioning of liver metabolism.


1. Where does phosphorylation occur?
Oxidative phosphorylation occurs in the inner mitochondrial membrane, in contrast to much of the citric acid cycle reactions and fatty acid oxidation occurring in the matrix.

2. What are the 3 types of phosphorylation?
Cells transmit energy and produce ATP by photophosphorylation, phosphorylation at the substratum level and/or oxidative phosphorylation, depending on the type of organism. Phosphorylation refers to a group of phosphates being bound to a molecule.

3. Does phosphorylation require ATP?
ATP. ATP. Within the mitochondrion, ATP, the “high-energy” exchange medium in the cell, is synthesized by the addition of a third group of phosphates to ADP in a process called oxidative phosphorylation. During glycolysis ATP is also synthesized by phosphorylation at the substratum level.

4. What is the purpose of phosphorylation?
Phosphorylation is the mechanism of integrating a group of phosphates into an organic molecule. It plays a critical role in regulating pathways to cellular processes such as cell apoptosis, cycle, development, and signal transduction.

5. What is phosphorylation and why is it important?
Enzymes (e.g., kinases, phosphotransferases) conduct both phosphorylation and dephosphorylation. In the fields of biochemistry and molecular biology phosphorylation is significant because it is a key reaction in protein and enzyme activity, sugar metabolism, and energy storage and release.

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