The recently described structure of bone morphogenetic protein 7 in complex with the extracellular domain of the activin type receptor II provides a new and important paradigm to add to the list of possible modes of receptor assembly. A new mode of a ligand-mediated cooperative receptor assembly without receptor-receptor contacts yields new and exciting insights into the molecular signal transduction mechanism in the transforming growth factor-beta superfamily.
Department of Physiological Chemistry II, Biocenter, University of Wuerzburg, Am Hubland, D-97074, Wuerzburg, Germany. sebald@biozentrum.uni-wuerzberg.de
