• Purity

  >90%, by SDS-PAGE under reducing conditions and visualized by silver stain

• Endotoxin Level

  <0.01 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by its binding ability in a functional ELISA. Immobilized Recombinant Mouse EphA8 Fc Chimera at 2 µg/mL (100 µL/well) can bind recombinant human Ephrin-A5 Fc Chimera with a linear range of    
  0.31-20 ng/mL.    
     Optimal dilutions should be determined by each laboratory for each application.  

• Source

  Mouse myeloma cell line, NS0-derived

  Mouse EphA8 (Gly27 - Arg540) Accession # O09127	DIEGRMD	Human IgG1 (Pro100 - Lys330)	6-His tag
  N-terminus			C-terminus

• Accession #

• N-terminal Sequence    
  Analysis

  Gly27

• Structure / Form

  Disulfide-linked homodimer

• Predicted Molecular Mass

  84.2 kDa (monomer)

• SDS-PAGE

  100-120 kDa, reducing conditions

Background: EphA8

EphA8, also known as Hek3 and Eek, is a 120 kDa glycosylated member of the Eph family of transmembrane receptor tyrosine kinases (1, 2). The A and B classes of Eph proteins are distinguished by Ephrin ligand binding preference but have a common structural organization. EphA4 binds and is activated by class A Ephrins but not class B Ephrins (3, 4). Eph-Ephrin interactions are widely involved in the regulation of cell migration, tissue morphogenesis, and cancer progression. The 514 amino acid (aa) extracellular domain (ECD) of mouse EphA8 contains an N-terminal Ephrin binding region, a cysteine-rich region, and two fibronectin type III domains (FnIII). The 442 aa cytoplasmic domain contains the tyrosine kinase domain and a sterile alpha motif (SAM) (3). Within the ECD, mouse EphA8 shares 97% and 99% aa sequence identity with human and rat EphA8, respectively. EphA8 is expressed in neurons in the mesencephalon of the developing brain, particularly in the rostral tectum and the superior colliculus (5 - 7). It is enriched at the tips of neurite processes and plays a role in projection of superior colliculus axons through the posterior commissure (6, 8). Its expression enhances neurite extension be means of a mechanism that does not require catalytic activity of the tyrosine kinase domain (9). Ephrin-mediated activation of the EphA8 kinase induces phosphorylation of tyrosine residues in the cytoplasmic domain, leading to association with signaling and scaffolding proteins and inhibition of cell-cell adhesion (4, 8, 10). Ligand binding can also promote the Integrin-mediated cellular adhesion to Fibronectin (11). This function, like the enhancement of neurite extension, does not require activation of the kinase domain (11).

• References:

1. Pasquale, E.B. (2005) Nat. Rev. Mol. Cell Biol. 6:462.

2. Merlos-Suarez, A. and E. Batlle (2008) Curr. Opin. Cell Biol. 20:194.

3. Park, S. and M.P. Sanchez (1997) Oncogene 14:533.

4. Choi, S. et al. (1999) Mol. Cells 9:440.

5. Koo, J. et al. (2003) Dev. Dyn. 226:596.

6. Park, S. et al. (1997) EMBO J. 16:3106.

7. Shim, S. et al. (2007) Mol. Cell. Biol. 27:1614.

8. Shin, J. et al. (2007) Mol. Cell. Biol. 27:8113.

9. Gu, C. et al. (2005) Oncogene 24:4243.

10. Choi, S. and S. Park (1999) Oncogene 18:5413.

11. Gu, C. and S. Park (2001) Mol. Cell. Biol. 21:4579.

• Long Name:

  Eph Receptor A8

• Entrez Gene IDs:

  2046 (Human); 13842 (Mouse)

• Alternate Names:

  Eek; EK3; EPH- and ELK-related kinase; EPH- and ELK-related tyrosine kinase; EPH receptor A8; EphA8; EPH-like kinase 3; ephrin type-A receptor 8; Hek3; hydroxyaryl-protein kinase; KIAA1459; protein-tyrosine kinase; tyrosine-protein kinase receptor EEK; tyrosylprotein kinase