The repulsive guidance molecule (RGM) family of molecules contains three uniquely structured GPI-linked glycoproteins that participate in a variety of activities. Termed RGM-A, -B and -C, they are 40-45 kDa in size, show generally nonoverlapping fetal expression patterns, and serve as BMP-4 receptors. RGM-A and -C are plasma membrane bound, while RGM-B is generally microsomal in location. RGM-A and -B are associated with neurons, while RGM-C regulates skeletal muscle and hepatocyte function.