protein tyrosine kinase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: ATP + a protein tyrosine = ADP + protein tyrosine phosphate. [RHEA:10596]

Protein tyrosine kinase activity is a crucial molecular function that involves the transfer of a phosphate group from ATP to a tyrosine residue on a target protein. This process, known as phosphorylation, plays a vital role in regulating a wide range of cellular processes, including signal transduction, cell growth, differentiation, and apoptosis. Tyrosine kinases are enzymes that catalyze this phosphorylation reaction, and their activity is tightly controlled to ensure proper cellular function.

The catalytic domain of tyrosine kinases typically consists of two lobes, an N-terminal lobe and a C-terminal lobe. The N-terminal lobe contains a glycine-rich loop and a catalytic loop, which are essential for ATP binding and catalysis. The C-terminal lobe contains a substrate-binding site, which recognizes and binds to the tyrosine residue on the target protein.

Upon activation, tyrosine kinases undergo a conformational change that brings the catalytic domain into close proximity with the substrate. This allows the kinase to efficiently transfer a phosphate group from ATP to the tyrosine residue. The phosphorylation event alters the conformation and/or activity of the target protein, leading to downstream signaling events.

Tyrosine kinases are often activated by a variety of stimuli, including growth factors, hormones, and cytokines. These signals trigger a cascade of events that ultimately lead to the activation of tyrosine kinases. The activated kinases then phosphorylate downstream target proteins, initiating signaling pathways that control cellular functions.

Mutations in tyrosine kinases can lead to uncontrolled cell growth and proliferation, which can contribute to the development of cancer. In fact, many tyrosine kinases are overexpressed or mutated in various types of cancer, making them attractive targets for cancer therapy.

Tyrosine kinase inhibitors are drugs that specifically block the activity of tyrosine kinases. These inhibitors are used to treat various types of cancer, including leukemia, lung cancer, and breast cancer.

In summary, protein tyrosine kinase activity is a critical molecular function that plays a central role in cell signaling and regulation. This process involves the phosphorylation of tyrosine residues on target proteins, leading to downstream signaling events that control cellular functions. Dysregulation of tyrosine kinase activity is associated with various diseases, including cancer, highlighting the importance of understanding and targeting these enzymes.'
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Proteins (136)

Compounds (907)