A tyrosine kinase (EC 2.7.1.112) is an enzyme that can transfer a phosphate group to a tyrosine residue in a protein; these enzymes are a subgroup of the larger class of protein kinases. Phosphorylation is an important function in signal transduction to regulate enzyme activity. The hormones that act on tyrosine kinase receptors are generally growth hormones and factors that promote cell division (e.g., insulin, insulin-like growth factor 1, epidermal-derived growth factor).
There are over 100 3D structures of tyrosine kinases available at the Protein Data Bank. An example is PDB 1IRK (http://www.rcsb.org/pdb/cgi/explore.cgi?pid=232131034361062&page=60&pdbId=1IRK), the crystal structure of the tyrosine kinase domain of the human insulin receptor.
The first non-receptor tyrosine kinase identified was the v-Srconcogenic protein. Most animal cells contain one or more members of the Src family of tyrosine kinases. A chicken sarcoma virus was found to carry mutated version of the normal cellular Src gene. The mutated v-src gene has lost the normal built-in inhibition of enzyme activity that is characteristic of cellular SRC (c-src) genes. SRC family members have been found to regulate many cellular processes. For example, the T-cell antigen receptor leads to intracellular signalling by activation of Lck and Fyn, two proteins that are structurally similar to Src.
Abl
Abl (Abelson leukemia virus protein, chromosome 9q34) is an important tyrosine kinase. This gene is fused with the bcr gene in a Philadelphia chromosome, the characteristic abnormality in chronic myelogenous leukemia (CML) and rarely in some other leukemia forms. The bcr-abl transcript is also a tyrosine kinase, which activates mediators of the cell cycle regulation system, leading to a clonal myeloproliferative disorder. The bcr-abl protein can be inhibited with the agent imatinib mesylate, which occupies the TK domain and inhibits bcr-abls influence on the cell cycle.
A tyrosinekinase (EC 2.7.1.112) is an enzyme that can transfer a phosphate group to a tyrosine residue in a protein; these enzymes are a subgroup of the larger class of proteinkinases.
The hormones that act on tyrosinekinase receptors are generally growth hormones and factors that promote cell division (e.g., insulin, insulin-like growth factor 1, epidermal-derived growth factor).
An example is PDB 1IRK, the crystal structure of the tyrosinekinase domain of the human insulin receptor.
The tyrosinekinase Lck is involved in regulation of mitochondrial apoptosis pathways.
The tyrosinekinase lck is critically involved in the growth transformation of human B lymphocytes.
Pervanadate induced activation of the tyrosinekinases lck and fyn (4- and 3-fold respectively) and a dramatic increase in tyrosinephosphorylation of cellular proteins, notably phospholipase C gamma 1.
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