Structural Basis for Autoinhibition of the EphB2 Receptor Tyrosine Kinase by the Unphosphorylated Juxtamembrane Region

• Published in: Cell 2001-09, Vol.106 (6), p.745-757
• Main Authors: Wybenga-Groot, Leanne E., Baskin, Berivan, Ong, Siew Hwa, Tong, Jiefei, Pawson, Tony, Sicheri, Frank
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino Acid Substitution; Animals; Binding Sites; Cell Membrane - physiology; Crystallography, X-Ray; Humans; Mice; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Phosphorylation; Protein Conformation; Protein Structure, Secondary; Receptor Protein-Tyrosine Kinases - antagonists & inhibitors; Receptor Protein-Tyrosine Kinases - chemistry; Receptor Protein-Tyrosine Kinases - metabolism; Receptor, EphB2; Recombinant Proteins - antagonists & inhibitors; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Sequence Alignment; Sequence Homology, Amino Acid
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/S0092-8674(01)00496-2

The Eph receptor tyrosine kinase family is regulated by autophosphorylation within the juxtamembrane region and the kinase activation segment. We have solved the X-ray crystal structure to 1.9 Å resolution of an autoinhibited, unphosphorylated form of EphB2 comprised of the juxtamembrane region and the kinase domain. The structure, supported by mutagenesis data, reveals that the juxtamembrane segment adopts a helical conformation that distorts the small lobe of the kinase domain, and blocks the activation segment from attaining an activated conformation. Phosphorylation of conserved juxtamembrane tyrosines would relieve this autoinhibition by disturbing the association of the juxtamembrane segment with the kinase domain, while liberating phosphotyrosine sites for binding SH2 domains of target proteins. We propose that the autoinhibitory mechanism employed by EphB2 is a more general device through which receptor tyrosine kinases are controlled.