Receptor tyrosine kinase which binds promiscuously transmembrane ephrin-B family ligands residing on adjacent cells, leading to contact-dependent bidirectional signaling into neighboring cells. The signaling pathway downstream of the receptor is referred to as forward signaling while the signaling pathway downstream of the ephrin ligand is referred to as reverse signaling. Generally has an overlapping and redundant function with EPHB2. Like EPHB2, functions in axon guidance during development. In addition to its role in axon guidance also plays an important redundant role with other ephrin-B receptors in development and maturation of dendritic spines and the formation of excitatory synapses. May control other aspects of development through regulation of cell migration and positioning (By similarity). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Heterotetramer upon binding of the ligand. The heterotetramer is composed of an ephrin dimer and a receptor dimer. Oligomerization is probably required to induce biological responses (By similarity). Present in 10-day embryonic brain and body tissues. Prominent expression in kidney. Lower expression in lung, and barely detectable in brain, liver, heart, skeletal muscle and thymus. Phosphorylated. Autophosphorylates upon ligand-binding. Autophosphorylation on Tyr-604 is required for interaction with SH2 domain-containing proteins (By similarity). Belongs to the protein kinase superfamily. Tyr protein kinase family. Ephrin receptor subfamily.