The secreted glycoprotein sclerostin has recently emerged as a key negative regulator of
Wnt signaling in bone and has stimulated considerable interest as a potential target for
therapeutics designed to treat conditions associated with low bone mass, such as
osteoporosis. We have determined the structure of sclerostin, which resulted in the
identification of a previously unknown binding site for heparin, suggestive of a functional role
in localizing sclerostin to the surface of target cells. We have also mapped the interaction …