• 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. When Recombinant Human EphA8 Fc Chimera is coated at 2 μg/mL (100 μL/well), the concentration of Biotinylayed Recombinant Human Ephrin-A5 Fc Chimera (Catalog # ) that produces 50% of the optimal binding response is 2-12 ng/mL.

• Source

  Mouse myeloma cell line, NS0-derived

  Human EphA8 (Glu31-Thr542) Accession # NP_065387	IEGRMD	Human IgG1 (Pro100-Lys330)
  N-terminus		C-terminus

• Accession #

• N-terminal Sequence    
  Analysis

  Glu31

• Structure / Form

  Disulfide-linked homodimer

• Predicted Molecular Mass

  83.2 kDa (monomer)

• SDS-PAGE

  94 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 512 amino acid (aa) extracellular domain (ECD) of human 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) (5). Within the ECD, human EphA8 shares 97% aa sequence identity with mouse and rat EphA8. EphA8 is expressed in neurons in the mesencephalon of the developing brain, particularly in the rostral tectum and the superior colliculus (6-8). It is enriched at the tips of neurite processes and plays a role in projection of superior colliculus axons through the posterior commissure (7, 9). Its expression enhances neurite extension by means of a mechanism that does not require catalytic activity of the tyrosine kinase domain (10). 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, 9, 11). Ligand binding can also promote the Integrin-mediated cellular adhesion to Fibronectin (12). This function, like the enhancement of neurite extension, does not require activation of the kinase domain (12).

• 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. Chan, J. and V.M. Watt (1991) Oncogene 6:1057.

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

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

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

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

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

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

12. 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