Modulators and modulation of the interaction between RGM and Neogenin

1. A method for identifying an agent which modulates the binding of a Repulsive Guidance Molecule (RGM) to a Neogenin, the method comprising the steps of: (a) forming a mixture comprising an isolated mammalian RGM and an isolated mammalian Neogenin, wherein the isolated mammalian Neogenin has the amino acid sequence of SEQ ID NO: 1; (b) incubating said mixture in the presence of an agent; and (c) detecting in the incubated mixture of step (b) the level of specific binding between said RGM and said Neogenin, wherein a difference in the detected level of specific binding of said RGM to said Neogenin in the presence of said agent relative to the level of specific binding in the absence of said agent indicates that said agent modulates the binding of said RGM to said Neogenin, wherein said RGM is RGM A or RGM B.

2. A method for monitoring the binding of a Repulsive Guidance Molecule (RGM), wherein said RGM is RGM A or RGM B to a Neogenin, the method comprising the steps of: (a) contacting a first protein comprising said RGM tagged with a visible stain or enzymatic signal, with a second protein which comprises the Neogenin, wherein said Neogenin has the amino acid sequence of SEQ ID NO: 1 and with a RGM A-specific antibody, or a RGM B specific antibody which will interfere in the binding between the tagged RGM A or RGM B and the Neogenin; (b) leaving the mixture for a time and under conditions where a domain of the RGM A or RGM B binds to a domain of the Neogenin; and (c) monitoring the binding of the first protein which comprises the tagged RGM, to the second protein which comprises the Neogenin, wherein a reduction in the visible stain or enzymatic signal indicates a reduction of tagged RGM binding to Neogenin due to the antibody interacting with said binding.