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Background
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Ephrin A6, a member of the ephrin family, elicits biological responses in retinal neurons. It binds with high affinity to several other EphA receptors and causes growth cone collapse in retinal explants. Ephrin-A6 expression is high at embryonic day 6 (E6) and at embryonic day 8 (E8), when retinal axons grow to their tectal targets, and then this Ephrin-A6 expression gradually declines at later developmental stages. This new ephrin plays a role in the establishment of visual system topography as observed by the asymmetric distribution of ephrin-A6 in retinal cells. High levels of expression of Eph-A6 in the macula of developing human retina showed localization of Eph-A6 to (GC) ganglion cells. Eph receptors and Ephrins have indeed been implicated in multiple aspects of synaptic function, including clustering and modulating N-methyl-D-aspartate receptors, modifying the geometry of postsynaptic terminals, and influencing long-term synaptic plasticity and memory. Eph A6, in line with a number of other Eph receptors and their ephrin ligands, is involved in neural circuits of learning and memory. Genetic inhibition of the ephrin receptor (Eph A6) in knockout mice produced behavioral deficits in tests of learning and memory. The gene for EphAR6 is present on chromosome 3q11.2
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