Recombinant Mouse RGM-A Protein, CF

Mouse repulsive guidance molecule (RGM‑A) is a 33 kDa GPI-linked member of an expanding RGM‑related family of neuronal and muscle-expressed membrane proteins (1, 2). It is synthesized as a 454 amino acid (aa) preproprotein that contains a 47 aa signal sequence, a 122 aa N-terminal prosegment, a 258 mature region (aa 170-427) and a 27 aa C-terminal prosegment (3, 4). The N-terminal prosegment contains an RGD tripeptide and the molecule's only two potential N‑linked glycosylation sites. The mature segment shows an abbreviated von Willebrand factor domain. Proteolytic processing occurs at an aspartic acid‑proline bond, creating a predicted 32 kDa mature region (3). There is one potential alternative start site at Met17. The mature region of mouse RGM-A is 93% and 87% aa identical to human and chick mature region RGM-A, respectively. Recognizing that RGM-A possesses a cleavage site between Asp169Pro170, it is suggested that membrane-expressed RGM-A may exist as a covalent heterodimer that links a GPI-anchored mature molecule with its prosegment (1, 4, 5). When compared to mouse RGM-B and C, the mature region of mouse RGM-A shows 77% and 76% aa identity, respectively (5, 6). Cells normally described as expressing RGM-A include neurons and oligodendroglia. But this select group is expanded to endothelium, microglia and leukocytes in areas of neuronal injury (7). Functionally, recombinant chick RGM has been reported to induce collapse of temporal but not nasal growth cones, and to repel temporal retinal axons in vitro. This suggests a role in the development of the retina-superior colliculus connection. In mice, RGM-A also induces growth cone collapse on primary DRG neurons (8). And in a mouse culture system, chick RGM-A is reported to be responsible for the layered segmentation of entorhinal cortical projections to the hippocampus (9). RGM reportedly binds to neogenin and BMP-2/4, with the latter binding occuring within the context of a BMPRI:ActRIIA:RGM-A receptor complex (10-13).