Ephrin-A4

EphrinA4, also known as LERK4 and EFL4 (1), is a member of the ephrin ligand family which binds members of the Eph receptor family. All ligands share a conserved extracellular sequence, which most likely corresponds to the receptor binding domain. This conserved sequence consists of approximately 125 amino acids and includes four invariant cysteines. The A-class ligands have a GPI anchor following the conserved sequence. EphrinA4 has been shown to bind EphA2, EphA3, EphA4, EphA5, EphA6, EphA7, and EphB1. The extracellular domains of human and mouse EphrinA4 share 80% amino acid identity. Only membrane-bound or Fc clustered ligands are capable of activating the receptor in vitro. While soluble monomeric ligands bind the receptor, they do not induce receptor autophosphorylation and activation. In vivo, the ligands and receptors display reciprocal expression. It has been found that nearly all receptors and ligands are expressed in developing and adult neural tissue. The Eph/ephrin families also appear to play a role in angiogenesis.