Kinase-defective receptor for members of the ephrin-B family. Binds to ephrin-B1 and ephrin-B2. Modulates cell adhesion and migration by exerting both positive and negative effects upon stimulation with ephrin-B2. Inhibits JNK activation, T cell receptor-induced IL-2 secretion and CD25 expression upon stimulation with ephrin-B2.
Expressed in brain. Expressed in non invasive breast carcinoma cell lines (at protein level). Strong expression in brain and pancreas, and weak expression in other tissues, such as heart, placenta, lung, liver, skeletal muscle and kidney. Expressed in breast non invasive tumors but not in metastatic lesions. Isoform 3 is expressed in cell lines of glioblastomas, anaplastic astrocytomas, gliosarcomas and astrocytomas. Isoform 3 is not detected in normal tissues.
Belongs to the protein kinase superfamily. Tyr protein kinase family. Ephrin receptor subfamily. Contains 2 fibronectin type-III domains. Contains 1 protein kinase domain. Contains 1 SAM (sterile alpha motif) domain.
The protein kinase domain is predicted to be catalytically inactive. Its extracellular domain is capable of promoting cell adhesion and migration in response to low concentrations of ephrin-B2, but its cytoplasmic domain is essential for cell repulsion and inhibition of migration induced by high concentrations of ephrin-B2.
Ligand-binding increases phosphorylation on tyrosine residues. Phosphorylation on tyrosine residues is mediated by transphosphorylation by the catalytically active EPHB1 in a ligand-independent manner. Tyrosine phosphorylation of the receptor may act as a switch on the functional transition from cell adhesion/attraction to de-adhesion/repulsion.