Receptor Tyrosine kinases |
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Protein Tyrosine Kinases: Receptor PTKs are comprised of an extracellular ligand-binding domain, a single transmembrane domain, and a cytoplasmic portion containing the catalytic core, as well as regulatory sequences. A general mechanism for ligand-induced activation of receptor tyrosine kinases has been established (Lemmon and Schlessinger, 1994 ), in which ligand binding to the extracellular domain induces receptor dimerization. Receptor dimerization in turn leads to activation of the catalytic protein tyrosine kinase domain and to tyrosine autophosphorylation. Phosphorylation of tyrosine residues that leads to generation of docking sites for SH2 (Src homology 2) and PTB (phosphotyrosine binding) domains of adaptor proteins (Pawson and Scott, 1997 ).
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