title: Crystal structure of an Eph receptor-ephrin complex.
abstract: The Eph family of receptor tyrosine kinases and their membrane-anchored ephrin ligands are important in regulating cell-cell interactions as they initiate a unique bidirectional signal transduction cascade whereby information is communicated into both the Eph-expressing and the ephrin-expressing cells. Initially identified as regulators of axon pathfinding and neuronal cell migration, Ephs and ephrins are now known to have roles in many other cell-cell interactions, including those of vascular endothelial cells and specialized epithelia. Here we report the crystal structure of the complex formed between EphB2 and ephrin-B2, determined at 2.7 A resolution. Each Eph receptor binds an ephrin ligand through an expansive dimerization interface dominated by the insertion of an extended ephrin loop into a channel at the surface of the receptor. Two Eph-Ephrin dimers then join to form a tetramer, in which each ligand interacts with two receptors and each receptor interacts with two ligands. The Eph and ephrin molecules are precisely positioned and orientated in these complexes, promoting higher-order clustering and the initiation of bidirectional signalling.
authors.affiliation: Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10021, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Himanen
authors.forename: K R
authors.initials: KR
authors.lastname: Rajashankar
authors.forename: M
authors.initials: M
authors.lastname: Lackmann
authors.forename: C A
authors.initials: CA
authors.lastname: Cowan
authors.forename: M
authors.initials: M
authors.lastname: Henkemeyer
authors.forename: D B
authors.initials: DB
authors.lastname: Nikolov
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018360:Crystallography, X-Ray; D019281:Dimerization; D036388:Ephrin-B2; D004926:Escherichia coli; D008024:Ligands; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry* / Q000378:metabolism; D036183:Receptor, EphB2; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D036388:Ephrin-B2; D008024:Ligands; D046911:Macromolecular Substances; D008565:Membrane Proteins; D011994:Recombinant Proteins; D020794:Receptor Protein-Tyrosine Kinases; D036183:Receptor, EphB2