Eph receptor tyrosine kinase family (Eph receptors) (Eph)

The Eph receptor tyrosine kinase family comprises the largest group of receptor tyrosine kinases and mediates contact-dependent cell–cell communication by binding membrane-anchored ephrin ligands, generating bidirectional signals: forward signaling through the Eph kinase in the receptor-expressing cell and reverse signaling in the ephrin-expressing cell. Humans express 14 Eph receptors subdivided into two classes based on sequence and ligand-binding: nine EphA receptors (EphA1–EphA8, EphA10) that preferentially bind GPI-anchored ephrin-As, and five EphB receptors (EphB1–EphB4, EphB6) that bind transmembrane ephrin-Bs; notable exceptions include cross-class interactions such as EphA4 with ephrin-B2/B3 and EphB2 with ephrin-A5. Eph receptors share a conserved architecture with an extracellular ephrin-binding domain, cysteine-rich region, two fibronectin type III repeats, a single-pass transmembrane helix, and a cytoplasmic region containing a juxtamembrane segment, tyrosine kinase domain, SAM motif, and PDZ-binding motif; EphA10 and EphB6 lack essential residues for kinase activity. Eph signaling influences axon guidance, vascular development and remodeling, tissue boundary formation, cell adhesion and migration, and synaptic plasticity, largely through regulation of Rho-family GTPases and modulation of Ras/MAPK, PI3K/Akt, JAK/STAT, and FAK pathways. Dysregulated Eph/ephrin signaling is implicated in cancer biology and angiogenesis, making Eph receptors attractive but challenging therapeutic targets; multiple investigational approaches include kinase inhibitors, antibodies, and ligand-based modulators that aim to inhibit kinase activity, disrupt ligand–receptor engagement, or drive receptor internalization.

Other names

Ephrin receptor familyErythropoietin-producing hepatocellular carcinoma receptor family (historical etymology of Eph)EphA receptors (EphA1–EphA8, EphA10)EphB receptors (EphB1–EphB4, EphB6)

Small-molecule kinase inhibition of the Eph intracellular tyrosine kinase domain (blocks forward signaling); Antibody- or ligand-directed receptor internalization and degradation (reduces signaling/repurposes signaling output); Ligand mimetics or ephrin-Fc constructs to cluster/activate or to competitively inhibit Eph–ephrin interactions, modulating bidirectional signaling; Disruption of Eph–ephrin binding at the extracellular interface (inhibits both forward and reverse signaling)