Epidermal growth factor receptor juxtamembrane region regulates allosteric tyrosine kinase activation.
Structural studies of the extracellular and tyrosine kinase domains of the epidermal growth factor receptor (ErbB-1) provide considerable insight into facets of the receptor activation mechanism, but the contributions of other regions of ErbB-1 have not been ascertained. This study demonstrates that the intracellular juxtamembrane (JM) region plays a vital role in the kinase activation mechanism. In the experiments described herein, the entire ErbB-1 intracellular domain (ICD) has been expressed in mammalian cells to explore the significance of the JM region in kinase activity. Deletion of the JM region (DeltaJM) results in a severe loss of ICD tyrosine phosphorylation, indicating that this region is required for maximal activity of the tyrosine kinase domain. Coexpression of DeltaJM and dimerization-deficient kinase domain ICD mutants revealed that the JM region is indispensable for allosteric kinase activation and productive monomer interactions within a dimer. Studies with the intact receptor confirmed the role of the JM region in kinase activation. Within the JM region, Thr-654 is a known protein kinase C (PKC) phosphorylation site that modulates kinase activity in the context of the intact ErbB-1 receptor; yet, the mechanism is not known. Whereas a T654A mutation promotes increased ICD tyrosine phosphorylation, the phosphomimetic T654D mutant generates a 50% reduction in ICD tyrosine phosphorylation. Similar to the DeltaJM mutants, the T654D mutant ICD failed to interact with a wild-type monomer. This study reveals an integral role for the intracellular JM region of ErbB-1 in allosteric kinase activation.
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA.
Kristina W
KW
Thiel
Graham
G
Carpenter
D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000201:enzymology; D002522:Chlorocebus aethiops; D019281:Dimerization; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017421:Sequence Analysis; D013912:Threonine / Q000737:chemistry / Q000378:metabolism
D013912:Threonine; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases