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Tyrosine phosphorylation is the addition of a phosphate (PO 4 3−) group to the amino acid tyrosine on a protein. It is one of the main types of protein phosphorylation . This transfer is made possible through enzymes called tyrosine kinases .
Tyrosine phosphorylation is considered to be one of the key steps in signal transduction and regulation of enzymatic activity. Phosphotyrosine can be detected through specific antibodies. Tyrosine residues may also be modified by the addition of a sulfate group, a process known as tyrosine sulfation. [17]
Tyrosine phosphorylation is a fast, reversible reaction, and one of the major regulatory mechanisms in signal transduction. Cell growth, differentiation, migration, and metabolic homeostasis are cellular processes maintained by tyrosine phosphorylation. The function of protein tyrosine kinases and protein-tyrosine phosphatase counterbalances ...
Tyrosine kinases belong to a larger class of enzymes known as protein kinases which also attach phosphates to other amino acids such as serine and threonine. Phosphorylation of proteins by kinases is an important mechanism for communicating signals within a cell (signal transduction) and regulating cellular activity, such as cell division.
Phosphorylation can occur on serine, threonine and tyrosine side chains (in other words, on their residues) through phosphoester bond formation, on histidine, lysine and arginine through phosphoramidate bonds, and on aspartic acid and glutamic acid through mixed anhydride linkages.
Dimerization of RTKs leads to autophosphorylation of tyrosine in the catalytic core of the dimer, and finally stimulation of the tyrosine kinase activity and cell signaling. [21] It is thus an example of a trans-autophosphorylation reaction, where one receptor subunit of the dimer phosphorylates the other subunit. [22]
Protein tyrosine (pTyr) phosphorylation is a common post-translational modification that can create novel recognition motifs for protein interactions and cellular localization, affect protein stability, and regulate enzyme activity.
A mutation may occur to replace a tyrosine (which needs to be phosphorylated in order to activate the protein) with an aspartic acid (which would not need to be phosphorylated). In a laboratory setting, the use of recombinant proteins to artificially introduce phosphomimetics is a common tool for studying phosphorylation and protein activation.