A core domain of the BMP2 proregion is sufficient for the biogenesis of mature homodimeric growth factor.

The large proregions of cystine knot growth factors exert several important biological functions. Previous results have shown that the proregion of BMP2 retards the activity of the mature growth factor. Hitherto, no information exists about the function of the BMP2 proregion during the biogenesis of the mature growth factor. Here, evidence is presented that the proregion is required for the secretion of BMP2 when present in covalent linkage to the mature domain. In trans complementation, i.e., with the proregion encoded by a separate plasmid, does not result in secretion of homodimeric mature growth factor. An extended variant of a previously in vitro characterized subdomain of the proregion, when being present in covalent linkage to the mature growth factor, restores secretion of mature BMP2, albeit at a reduced level.