Phosphorylation and Dephosphorylation process is controlled by the Enzymes. Enzymes play a great role in the Phosphorylation and Dephosphorylation process.
- Phosphorylation reactions are catalyzed by a family of enzymes called protein kinases that use adenosine triphosphate (ATP) as a phosphate donor.
- Phosphate groups are cleaved from phosphorylated enzymes by the action of phosphoprotein phosphatases
- Amino acids with –OH groups are targets for phosphorylation.
A significant instance of phosphorylation regulation is seen in muscle and liver glycogen phosphorylase that catalyzes the following response
Glycogen phosphorylase occurs in two forms:
- the more active phosphorylase a and
- the less active phosphorylase b.
The breakdown of glycogen is regulated by variations in the ratio of the two forms of glycogen phosphorylase a and b.
How can enzyme activity be controlled by phosphorylation?
−Phosphorylation relates to a phosphate being added to one of a protein’s amino acid side chains.
−Phosphates are charged negatively (with each phosphate group carrying two adverse charges) to alter the protein’s features by adding them to a protein.
−This shift is often a conformational change, which causes the protein to shift its structure.
Change in enzymatic composition with phosphorylation:
Enzymatic conformational changes in phosphorylation are dramatically apparent from the Insulin Receptor Kinase (IRK) structures determined in the phosphorylated and non-phosphorylated states.