• We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Logo of prosciprotein sciencecshl presssubscriptionsetoc alertsthe protein societyjournal home
Protein Sci. Oct 1999; 8(10): 1954–1961.
PMCID: PMC2144140

Solution structure of the receptor tyrosine kinase EphB2 SAM domain and identification of two distinct homotypic interaction sites.


The sterile alpha motif (SAM) is a protein interaction domain of around 70 amino acids present predominantly in the N- and C-termini of more than 60 diverse proteins that participate in signal transduction and transcriptional repression. SAM domains have been shown to homo- and hetero-oligomerize and to mediate specific protein-protein interactions. A highly conserved subclass of SAM domains is present at the intracellular C-terminus of more than 40 Eph receptor tyrosine kinases that are involved in the control of axonal pathfinding upon ephrin-induced oligomerization and activation in the event of cell-cell contacts. These SAM domains appear to participate in downstream signaling events via interactions with cytosolic proteins. We determined the solution structure of the EphB2 receptor SAM domain and studied its association behavior. The structure consists of five helices forming a compact structure without binding pockets or exposed conserved aromatic residues. Concentration-dependent chemical shift changes of NMR signals reveal two distinct well-separated areas on the domains' surface sensitive to the formation of homotypic oligomers in solution. These findings are supported by analytical ultracentrifugation studies. The conserved Tyr932, which was reported to be essential for the interaction with SH2 domains after phosphorylation, is buried in the hydrophobic core of the structure. The weak capability of the isolated EphB2 receptor SAM domain to form oligomers is supposed to be relevant in vivo when the driving force of ligand binding induces receptor oligomerization. A formation of SAM tetramers is thought to provide an appropriate contact area for the binding of a low-molecular-weight phosphotyrosine phosphatase and to initiate further downstream responses.

Full Text

The Full Text of this article is available as a PDF (3.7M).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Barr MM, Tu H, Van Aelst L, Wigler M. Identification of Ste4 as a potential regulator of Byr2 in the sexual response pathway of Schizosaccharomyces pombe. Mol Cell Biol. 1996 Oct;16(10):5597–5603. [PMC free article] [PubMed]
  • Bork P, Koonin EV. Predicting functions from protein sequences--where are the bottlenecks? Nat Genet. 1998 Apr;18(4):313–318. [PubMed]
  • Brückner K, Pasquale EB, Klein R. Tyrosine phosphorylation of transmembrane ligands for Eph receptors. Science. 1997 Mar 14;275(5306):1640–1643. [PubMed]
  • Davis S, Gale NW, Aldrich TH, Maisonpierre PC, Lhotak V, Pawson T, Goldfarb M, Yancopoulos GD. Ligands for EPH-related receptor tyrosine kinases that require membrane attachment or clustering for activity. Science. 1994 Nov 4;266(5186):816–819. [PubMed]
  • Grzesiek S, Bax A. Amino acid type determination in the sequential assignment procedure of uniformly 13C/15N-enriched proteins. J Biomol NMR. 1993 Mar;3(2):185–204. [PubMed]
  • Holland SJ, Gale NW, Mbamalu G, Yancopoulos GD, Henkemeyer M, Pawson T. Bidirectional signalling through the EPH-family receptor Nuk and its transmembrane ligands. Nature. 1996 Oct 24;383(6602):722–725. [PubMed]
  • Holm L, Sander C. Protein structure comparison by alignment of distance matrices. J Mol Biol. 1993 Sep 5;233(1):123–138. [PubMed]
  • Koradi R, Billeter M, Wüthrich K. MOLMOL: a program for display and analysis of macromolecular structures. J Mol Graph. 1996 Feb;14(1):51–32. [PubMed]
  • Kyba M, Brock HW. The SAM domain of polyhomeotic, RAE28, and scm mediates specific interactions through conserved residues. Dev Genet. 1998;22(1):74–84. [PubMed]
  • Murzin AG, Brenner SE, Hubbard T, Chothia C. SCOP: a structural classification of proteins database for the investigation of sequences and structures. J Mol Biol. 1995 Apr 7;247(4):536–540. [PubMed]
  • Nilges M, Clore GM, Gronenborn AM. Determination of three-dimensional structures of proteins from interproton distance data by dynamical simulated annealing from a random array of atoms. Circumventing problems associated with folding. FEBS Lett. 1988 Oct 24;239(1):129–136. [PubMed]
  • Orioli D, Klein R. The Eph receptor family: axonal guidance by contact repulsion. Trends Genet. 1997 Sep;13(9):354–359. [PubMed]
  • Ponting CP. SAM: a novel motif in yeast sterile and Drosophila polyhomeotic proteins. Protein Sci. 1995 Sep;4(9):1928–1930. [PMC free article] [PubMed]
  • Rafferty JB, Sedelnikova SE, Hargreaves D, Artymiuk PJ, Baker PJ, Sharples GJ, Mahdi AA, Lloyd RG, Rice DW. Crystal structure of DNA recombination protein RuvA and a model for its binding to the Holliday junction. Science. 1996 Oct 18;274(5286):415–421. [PubMed]
  • Sawaya MR, Pelletier H, Kumar A, Wilson SH, Kraut J. Crystal structure of rat DNA polymerase beta: evidence for a common polymerase mechanism. Science. 1994 Jun 24;264(5167):1930–1935. [PubMed]
  • Schultz J, Ponting CP, Hofmann K, Bork P. SAM as a protein interaction domain involved in developmental regulation. Protein Sci. 1997 Jan;6(1):249–253. [PMC free article] [PubMed]
  • Stapleton D, Balan I, Pawson T, Sicheri F. The crystal structure of an Eph receptor SAM domain reveals a mechanism for modular dimerization. Nat Struct Biol. 1999 Jan;6(1):44–49. [PubMed]
  • Stein E, Cerretti DP, Daniel TO. Ligand activation of ELK receptor tyrosine kinase promotes its association with Grb10 and Grb2 in vascular endothelial cells. J Biol Chem. 1996 Sep 20;271(38):23588–23593. [PubMed]
  • Stein E, Lane AA, Cerretti DP, Schoecklmann HO, Schroff AD, Van Etten RL, Daniel TO. Eph receptors discriminate specific ligand oligomers to determine alternative signaling complexes, attachment, and assembly responses. Genes Dev. 1998 Mar 1;12(5):667–678. [PMC free article] [PubMed]
  • Thanos CD, Goodwill KE, Bowie JU. Oligomeric structure of the human EphB2 receptor SAM domain. Science. 1999 Feb 5;283(5403):833–836. [PubMed]

Articles from Protein Science : A Publication of the Protein Society are provided here courtesy of The Protein Society


Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...


Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...