Structure and General Function of Nonreceptor Tyrosine Kinases

1 Structure and General Function of Nonreceptor Tyrosine Kinases 

Permanent or transient association with subcellular structures, and variable subcellular distribution, are characteristic for the cytoplasmic tyrosine kinases. Tire nonreceptor tyrosine kinases are intracellular effector molecules that can associate with specific substrates during the process of signal transduction and activate these by tyrosine phosphorylation, to pass on the signal. Many of the functions of the nonreceptor tyrosine kinases are performed in the iimnediate vicinity of the cell membrane, whether a signal is received from an activated membrane receptor or a signal is passed on to a membrane-associated protein. 

In Fig. 8.14, the structures of some nonreceptor tyrosine kinases are shown schematically (review Taniguchi, 1995). Tire nonreceptor tyrosine kinases can be divided into different families based on sequence homology the Src family is the best characterized. In addition to the catalytic domain, the nonreceptor tyrosine kinases often have SH2 and SH3 domains responsible for specific association with substrate proteins. Nonreceptor tyrosine kinases that contain both SH2 and SH3 domains may be involved in signal transduction in larger protein complexes. 

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