Question

Why do you think that phosphorylation and dephosphorylation has evolved to the point that it has such a prominent role switching proteins on and off in signaling pathways? (as opposed to, for example, using the allosteric binding of small molecules)

Answer 1

Solution

Role of phosphorylation and dephosphorylation-

• Biological thermodynamics of energy-requiring reactions
  • Phosphorylation of Na+/K+-ATPase during the transport of sodium (Na+) and potassium (K+) ions across the cell membrane in osmoregulation to maintain homeostasis of the body's water content.
• Mediates enzyme inhibition
  • Phosphorylation of the enzyme GSK-3 by AKT (Protein kinase B) as part of the insulin signaling pathway.
  • Phosphorylation of src tyrosine kinase (pronounced "sarc") by C-terminal Src kinase (Csk) induces a conformational change in the enzyme, resulting in a fold in the structure, which masks its kinase domain, and is thus shut "off".

In enzyme allosteric regulation it may be just change the activity of single reaction to stop any metablic patheay for its regulation.

While phosphorylation and dephosphorylation can activate or deactivate any enzyme, protein etc. To change whole process which involve in whole signaling cascade.

And it takes part in signal amplification process.but enzyme allosteric regulation is not amplification process.

So there is about 3 to 4 percent of genome encodes for kinase and phosphatase for phosphorylation amd dephosphorylation.