Biologically active BMP-2 in early Xenopus laevis embryos

In this study, we attempted to purify the dimeric BMP-2 from extracts of Xenopus embryos in order to show the presence of BMP-2 activity in the embryos. Immunoreactive BMP-2 protein was found to be a homodimer of an 18 kDa BMP-2 polypeptide linked through disulfide bridge(s). Biological activities of the partially purified dimeric BMP-2 were examined in vitro. The Xenopus BMP-2 induced alkaline phosphatase in a dose-dependent manner in cultured osteoblastic cells, MC3T3-E1. The inducing activity was synergistically enhanced by the presence of retinoic acid. The results showed that the dimeric form of Xenopus BMP-2 has an indistinguishable biological activity from that of mammalian BMP-2.