Tyrosine Kinase

About Tyrosine kinase:

Tyrosine kinase is a type of enzyme that can transfer phosphate groups from ATP to protein in the cell. Tyrosine kinases are, therefore, a type of protein kinase.

Tyrosine kinase Function
Kinases, like transferases, are responsible for catalyzing the transfer of phosphoryl groups from a nucleoside triphosphate donor to an acceptor molecule. Thus, they are involved in ATP metabolism and a crucial part of cellular respiration.
While tyrosine kinases are a subclass of protein kinases, they also have a variety of functions throughout the cell and are critical for reacting to events in the body.
Tyrosine kinase activity, for instance, regulates cell cycle control and the properties of transcription factors. It assists in the process of mitogenesis and the induction of mitosis.
The degree to which cells grow and develop may also respond to tyrosine kinase activity. Kinases are involved in energy sensing, telling the cell whether it should use energy to reproduce or conserve its resources until more food comes along. Tyrosine kinases have been observed to help stabilize DNA, suggesting that they have a reparative role in the cell, especially when the conditions for reproduction are not met.

Tyrosine kinase Interactions
Tyrosine kinases may have substantial clinical significance. Evidence suggests that excessive levels of tyrosine kinase may not be beneficial for the body. Genetic mutations in which the levels of tyrosine kinase are perpetually elevated are associated with the formation of several specific cancers. Many drug development companies are now looking at molecules that can inhibit the action of tyrosine kinases in the body in an attempt to prevent the disease from taking hold.
Clinical trials investigating the effect of tyrosine kinase inhibitors are ongoing. One study using the drug Gefitinib appears to have had favorable results in patients with non-small cell lung cancer.
Certain types of cancers do not respond well to standard chemotherapy treatments, particularly gastrointestinal stromal tumors. Researchers have found that certain types of tyrosine inhibitors, such as imatinib, are useful in these cases. These tumors are characterized by being bundles of crosslinked smaller tumors. The belief is that tyrosine inhibitors prevent the excessive division of these kinds of cells, reducing their growth rate.
Enhanced activity of tyrosine kinase is also related to a host of other health problems. For instance, cells with elevated tyrosine kinase tend to experience difficulties in cell division. Higher than normal levels are also associated with chronic conditions, such as psoriasis and atherosclerosis.

Tyrosine kinase Structure
Tyrosine kinase contains many of the structures common to practically all protein kinases, even if the specific structure of the molecule is somewhat different from other types of protein kinase.
Tyrosine kinases have an ATP binding site and two peptide sequences. They also sometimes have a catalytic site made of amino acid. More than 100 structures of tyrosine kinases are now held in the Protein Data Bank.
Other factors regulate most tyrosine kinase enzymes. Many, for instance, are bound reversibly by a protein. Recycled tyrosine kinases eventually find their way back to the lysosome, where they become an essential component of the digestion process.