peptidyl-tyrosine dephosphorylation involved in inactivation of protein kinase activity

Definition

Target type: biologicalprocess

Any peptidyl-tyrosine dephosphorylation that is involved in inactivation of protein kinase activity. [PMID:7501024]

Peptidyl-tyrosine dephosphorylation is a critical process in the inactivation of protein kinase activity. Protein kinases, key regulators of cellular processes, are enzymes that catalyze the transfer of a phosphate group from ATP to a specific tyrosine residue on a protein substrate. This phosphorylation event typically activates the protein kinase, enabling it to phosphorylate other target proteins and propagate signaling cascades. However, to maintain cellular homeostasis and prevent uncontrolled signaling, protein kinases must be inactivated. Dephosphorylation of the activated tyrosine residue on the kinase itself is a primary mechanism for this inactivation.

This dephosphorylation process is carried out by protein tyrosine phosphatases (PTPs). These enzymes are highly specific for phosphotyrosine residues and utilize a catalytic mechanism involving a cysteine residue in their active site. The cysteine residue forms a transient covalent bond with the phosphate group, facilitating its removal from the tyrosine residue.

The removal of the phosphate group disrupts the conformation of the protein kinase's active site, rendering it unable to bind ATP or its protein substrates. Consequently, the kinase becomes inactive, halting the phosphorylation cascade and signaling pathway.

In addition to direct dephosphorylation of the activated tyrosine residue, other mechanisms may contribute to the inactivation of protein kinases. These include:

* **Protein-protein interactions:** Some protein kinases are inactivated through interactions with inhibitory proteins that bind to their active site, blocking substrate access.
* **Allosteric regulation:** Structural changes in the kinase, induced by binding of regulatory molecules or by phosphorylation at other sites, can alter its activity.

Overall, the dephosphorylation of peptidyl-tyrosine residues by PTPs represents a critical step in the regulation of protein kinase activity. This precise control of kinase function is essential for maintaining cellular homeostasis and coordinating diverse biological processes.'
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Proteins (3)

Compounds (220)