Tyrosine kinase

Tyrosine kinase (TK) transfers a phosphate group from ATP to tyrosine residues of proteins. Mutated TK can cause unregulated growth of the cell and their inhibitors can be effective cancer treatment. TKs are classified as receptor-TK which are membrane-attached and cytoplasmic non-receptor TKs. TK contains, starting from the N-terminal, SH4 – a membrane attachment domain; SH3 and SH2 domains which are a sequence-specific phosphotyrosine binding domains with roles in protein-protein interactions and the SH1 catalytic kinase domain. Staurosporine inhibits TK and prevents ATP binding to it.

For Abelson tyrosine kinase see:

• Bcr-Abl and Imatinib (STI571 or Gleevec).
  

For Src tyrosine kinase see:

• SRC
  

See also

• Proto-oncogene tyrosine-protein kinase
  
• Tyrosine Kinase Inhibitor Pharmacokinetics.

For references see Treatments:TYKI References.

Traditional Chinese medicine as dual guardians against hypertension and cancer? ^[1]

functions as a signal protein and is implicated in various diseases. The carboxyl terminal of Src kinase is important in regulating conformation and activity of Src. Src protein is locked as an inward folding conformation through binding between the phosphorylated Tyr527 and the SH2 domain under normal inactive conditions. Src is activated when dephosphorylation of Tyr527 and phosphorylation of Tyr419 occurs. From N-terminal to C-terminal, Src is composed of a (residues 270–340; colored in violet) which binds adenosine triphosphate (ATP) and a (residues 345–523; colored in green) which binds with substrates. The ATP binding site is also partially located in the larger lobe. By regulating the alpha-helix structure, the large lobe can move toward or away from the small lobe, opening or closing the cleft between the two lobes. The Src catalytic site is located within the cleft. An open conformation allows the entrance of ATP into the cleft and exit of adenosine diphosphate (ADP) from the cleft. Drugs that can either interact with the residues (404–432) on the activation loop or inhibit the activation loop from moving away and opening the cleft as a result of Tyr419 phosphorylation can effectively inhibit Src activity. In this in vivo study, and have multiple stable interactions with the two Src cleft loops while simultaneously interacting with Asp407, hindering the activation loop from activation. Considering the aforementioned interactions with Src and high affinity with EGFR, HER2, and HSP90, we suggest that Angeliferulate and HMID which both originate from the TCM Angelica sinensis may have potential as multi-targeting drug leads.