Member of the repulsive guidance molecule (RGM) family that contributes to the patterning of the developing nervous system (By similarity). Acts as a bone morphogenetic protein (BMP) coreceptor that potentiates BMP signaling (By similarity). Promotes neuronal adhesion (By similarity). May inhibit neurite outgrowth. Homooligomer (By similarity). Interacts with DRGX (By similarity). Interacts with BMP2 and BMP4 (By similarity). Interacts with the BMP type I receptors ACVR1, BMPR1A and BMPR1B and with the BMP type II receptor ACVR2B (By similarity). The functional complex with its receptor NEO1/neogenin appears to be a heterotetramer with a 2:2 stoichiometry, RGM molecules acting as staples that bring two NEO1 receptors together without interacting themselves, this arrangement leads to activation of downstream signaling via RhoA. GPI-anchored. Autocatalytically cleaved at low pH; the two chains remain linked via two disulfide bonds. Belongs to the repulsive guidance molecule (RGM) family. Extended N-terminus. Intron retention.