EFNA3 belongs to the ephrin （EPH） family. The ephrins and EPH-related receptors include the largest subfamily of receptor protein-tyrosine kinases which have been implicated in mediating developmental events， especially in the nervous system and in erythropoiesis. Ephrins are divided into the ephrin-A （EFNA） class and the ephrin-B （EFNB） class， based on their structures and sequence relationships. The Ephrins from the EFNA class are anchored to the membrane by a glycosylphosphatidylinositol linkage， while the others from the EFNB class are transmembrane proteins.
