title: Leucine motif-dependent tyrosine autophosphorylation of type III receptor tyrosine kinases.
abstract: Activation loop tyrosine autophosphorylation is an essential requirement for full kinase activation of receptor tyrosine kinases (RTKs). However, mechanisms involved are not fully understood. In general, kinase domains of RTKs are folded into two main lobes, NH2- and COOH-terminal lobes. The COOH-terminal lobe of vascular endothelial growth factor receptor-2 (VEGFR-2) is folded into seven alpha-helices (alphaD-alphaI). In the studies presented here we demonstrate that leucine residues of helix I (alphaI) regulate tyrosine autophosphorylation and phosphotransferase activity of VEGFR-2. The presence of leucines 1158, 1161, and 1162 are essential for tyrosine autophosphorylation and kinase activation of VEGFR-2 and are involved in helix-helix packing via hydrophobic interactions. The presence of leucine 1158 is critical for kinase activation of VEGFR-2 and appears to interact with alphaE, alphaF, alphaH, and beta7. The analogous residue, leucine 957 on platelet-derived growth factor receptor-beta and leucine 910 on colony stimulating factor-1R are also found to be critical for tyrosine autophosphorylation of these receptors. Leucines 1161 and 1162 are also involved in helix-helix packing but they play a less critical role in VEGFR-2 activation. Thus, we conclude that leucine motif-mediated helix-helix interactions are critical for kinase regulation of type III RTKs. This mechanism is likely to be shared with other kinases and might provide a basis for the design of a novel class of tyrosine kinase inhibitors.
authors.affiliation: Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
authors.forename: Rosana D
authors.initials: RD
authors.lastname: Meyer
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Qian
authors.forename: Hwai-Chen
authors.initials: HC
authors.lastname: Guo
authors.forename: Nader
authors.initials: N
authors.lastname: Rahimi
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000409:Alanine / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D015153:Blotting, Western; D002457:Cell Extracts / Q000737:chemistry; D002460:Cell Line; D003115:Colony-Stimulating Factors / Q000737:chemistry / Q000378:metabolism; D016895:Culture Media, Serum-Free; D004730:Endothelium, Vascular / Q000166:cytology; D004789:Enzyme Activation; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007930:Leucine / Q000737:chemistry* / Q000235:genetics; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis / Q000145:classification* / Q000378:metabolism*; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014443:Tyrosine / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D002457:Cell Extracts; D003115:Colony-Stimulating Factors; D016895:Culture Media, Serum-Free; D011994:Recombinant Proteins; D014443:Tyrosine; D000255:Adenosine Triphosphate; D020794:Receptor Protein-Tyrosine Kinases; D020797:Receptor, Platelet-Derived Growth Factor beta; D040301:Vascular Endothelial Growth Factor Receptor-2; D007930:Leucine; D000409:Alanine