During development, organizing centres at key locations in the embryo secrete morphogens that become distributed in a concentration gradient. It is thought that cells along the gradient adopt different fates depending on the concentration of the morphogen they encounter. In the 22 March Nature, three studies shed light on the elaborate regulation of some potent morphogens — members of the bone morphogenetic protein (BMP) family.

All three studies focus on the role of the Twisted gastrulation (Tsg) protein and find that, in both vertebrates and invertebrates, this protein binds to members of the BMP family, preventing them from signalling. The authors — Jeffrey Ross of the University of Minnesota and co-workers, Ian Scott of the University of Wisconsin Medical School and co-workers, and Chenbei Chang of Rockefeller University and colleagues — studied Tsg function in Drosophila (Nature 2001, 410:479-483), Xenopus (Nature 2001, 410:475-478) and the...