Ephrins

Abstract

Ephrins are cell surface proteins that bind to the Eph family of receptor tyrosine kinases. Cell‐surface‐tethered ephrin‐A ligands principally activate EphA receptors, and transmembrane ephrin‐B ligands primarily activate EphB receptors. Ephs and ephrins influence many developmental processes, including compartmentalisation, cell migration, axon guidance and angiogenesis. These developmental functions arise as Ephrin–Eph interactions that shape cellular behaviours, including adhesion, migration and synaptic plasticity. Eph receptors communicate with the cytoskeleton through differential activation of small GTPases downstream of their tyrosine kinase activity. In addition to stimulating Eph receptors, ephrins signal within the cell which expresses them, a phenomenon termed ‘reverse signalling’. Ephrin‐B reverse signalling relies in part on phosphorylation of the cytoplasmic tail and recruitment of cytoplasmic proteins. Both ephrins and Ephs can modify internalisation and trafficking of other cell surface effector molecules. Cell surface receptors and ligands involved in intracellular signalling. Similar or identical molecular signals may observed in development and repair process. Primordial cells differentiate into various cell types during development. Tissue organisation and organ development from constituent cell types by compartmentalisation, cell–cell attraction and repulsion during the development. Dysregulated or abnormal cell–cell signalling lead to pathogenesis.