Figure 2.

ProBMP-4 is cleaved at two sites within the prodomain in vivo. RNAs encoding FLAG-tagged BMP-4 precursors were injected into Xenopus oocytes that were metabolically labeled, and FLAG-tagged proteins immunoprecipitated. Bands corresponding to uncleaved proBMP-4, intact prodomain following cleavage at the S1 site, and amino-terminal prodomain fragment following cleavage at the S2 site are indicated. Differences in the relative level of prodomain cleaved from each precursor were not reproducible.