When there is a phosphorylation by certain kinases to respective protein then why specfic kinases modifies specific protein accordingly. How this mere po4 is so specific though their stoichiometry is same in all the cases?
I think you are asking how specific kinases recognize specific targets for phosphorylation. The answer is that there is a protein-protein interaction that recruits the kinase to the target based on recognition of a structural motif. Then the catalytic site recognizes a peptide sequence motif for phosphorylation. Here is an article on the subject:
http://www.ncbi.nlm.nih.gov/pubmed/15655379
Yes, that specific kinases recognize specific targets for phosphorylation but enzymatically each kinase add a PO4 group to a protein which leads to conformational change. But i wanted to know how a mere PO4 group which is same for all leads to different conformational change for different protein. How this phosphorylation can make such accurate conformation or whats is the physics behind this chemistry?
Phosphorylation introduces a negative charge on the protein that was not there before. This charge changes the forces between amino acid residues and can thereby alter the three-dimensional structure of the protein. The precise nature of these changes depends upon the protein, since each protein is different. Even small changes in the structure of a protein can have profound effects on its function, such as by affecting the structure of the catalytic site of an enzyme..
Additionally, the phosphate group can contribute to a site of protein-protein interaction. Such interactions can form the basis for regulation of metabolic pathways, gene transcription, and so forth.
Thank you Sir, but can we quantitatively estimate the forces and measure accurately protein conformatinal change may be the angle shift?
The conformational change can be observed by x-ray crystallography by comparing the crystal structures of the unphosphorylated and phosphorylated proteins, if crystals can be obtained in each case. For small proteins, multidimensional NMR can also be used to solve the structures in solution. I don't know how the forces can be measured experimentally, but they can probably be calculated using molecular dynamics or some other computational technique.
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