2b0u
From Proteopedia
The Structure of the Follistatin:Activin Complex
Structural highlights
FunctionINHBA_HUMAN Inhibins and activins inhibit and activate, respectively, the secretion of follitropin by the pituitary gland. Inhibins/activins are involved in regulating a number of diverse functions such as hypothalamic and pituitary hormone secretion, gonadal hormone secretion, germ cell development and maturation, erythroid differentiation, insulin secretion, nerve cell survival, embryonic axial development or bone growth, depending on their subunit composition. Inhibins appear to oppose the functions of activins. Evolutionary ConservationCheck, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedTGF-beta ligands stimulate diverse cellular differentiation and growth responses by signaling through type I and II receptors. Ligand antagonists, such as follistatin, block signaling and are essential regulators of physiological responses. Here we report the structure of activin A, a TGF-beta ligand, bound to the high-affinity antagonist follistatin. Two follistatin molecules encircle activin, neutralizing the ligand by burying one-third of its residues and its receptor binding sites. Previous studies have suggested that type I receptor binding would not be blocked by follistatin, but the crystal structure reveals that the follistatin N-terminal domain has an unexpected fold that mimics a universal type I receptor motif and occupies this receptor binding site. The formation of follistatin:BMP:type I receptor complexes can be explained by the stoichiometric and geometric arrangement of the activin:follistatin complex. The mode of ligand binding by follistatin has important implications for its ability to neutralize homo- and heterodimeric ligands of this growth factor family. The structure of the follistatin:activin complex reveals antagonism of both type I and type II receptor binding.,Thompson TB, Lerch TF, Cook RW, Woodruff TK, Jardetzky TS Dev Cell. 2005 Oct;9(4):535-43. PMID:16198295[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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