E3355-01D

EphA1, Fc Chimera, Recombinant, Human (Ephrin-A1, EPH-related Receptor Tyrosine Kinase Ligand 1, LERK-1, Immediate Early Response Protein B61, Tumor Necrosis Factor alpha-induced Protein 4, TNF alpha-induced Protein 4, EFNA1, EPLG1, LERK1, TNFAIP4)

Ephrin-A1, also known as B61 and LERK-1, is a member of the Ephrin-A family of GPI-anchored ligands that bind and induce the tyrosine autophosphorylation of Eph receptors. Ephrin-A ligands are structurally related to the extracellular domains of the transmembrane Ephrin-B ligands. Eph-Ephrin interactions are widely involved in the regulation of cell migration, tissue morphogenesis, and cancer progression. Human Ephrin-A1 is synthesized with an 18aa signal peptide, a 164aa mature chain, and a 23aa C-terminal propeptide which is removed prior to GPI linkage of Ephrin-A1 to the membrane. It can also be released as a soluble molecule. The mature 21-25kD human Ephrin-A1 shares 85% aa sequence identity with mouse and rat Ephrin-A1. Alternate splicing generates an additional isoform that lacks 22aa in the juxtamembrane region. This short isoform is also expressed on the cell surface and exhibits weakened binding to EphA2. Ephrin-A1 is widely expressed on endothelial and epithelial cells, particularly in the lung, intestine, liver, and skin. It is expressed on resting CD4+ T cells but is down-regulated following activation. Ligation of Ephrin-A1 on CD4+ T cells inhibits cell proliferation and activation, although soluble Ephrin-A1 can promote T cell chemotaxis. In cancer, Ephrin-A1 is expressed by tumor cells as well as on the tumor-associated vasculature. It inhibits tumor cell proliferation and migration but also supports tumor growth by promoting angiogenesis. Soluble Ephrin-A1 additionally promotes neuronal survival and neurite extension.