This family consists of the N-terminal region of several mammalian and one bird sequence from Gallus gallus (Chicken). All of the mammalian proteins are hypothetical and have no known function but Swiss:Q8JG54 from the chicken is annotated as being a repulsive guidance molecule (RGM). RGM is a GPI-linked axon guidance molecule of the retinotectal system. RGM is repulsive for a subset of axons, those from the temporal half of the retina. Temporal retinal axons invade the anterior optic tectum in a superficial layer, and encounter RGM expressed in a gradient with increasing concentration along the anterior-posterior axis. Temporal axons are able to receive posterior-dependent information by sensing gradients or concentrations of guidance cues. Thus, RGM is likely to provide positional information for temporal axons invading the optic tectum in the stratum opticum [1].

1: RGM is a repulsive guidance molecule for retinal axons. Monnier PP, Sierra A, Macchi P, Deitinghoff L, Andersen JS, Mann M, Flad M, Hornberger MR, Stahl B, Bonhoeffer F, Mueller BK; Nature 2002;419:392-395. PMID:12353034