1s4y is a 4 chain structure with sequence from Homo sapiens and Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
A new crystal structure of activin in complex with the extracellular domain of its type II receptor (ActRIIb-ECD) shows that the ligand exhibits an unexpected flexibility. The motion in the activin dimer disrupts its type I receptor interface, which may account for the disparity in its affinity for type I versus type II receptors. We have measured the affinities of activin and its antagonist inhibin for ActRIIb-ECD and found that the affinity of the 2-fold symmetric homodimer activin for ActRIIb-ECD depends on the availability of two spatially coupled ActRIIb-ECD molecules, whereas the affinity of the heterodimer inhibin does not. Our results indicate that activin's affinity for its two receptor types is greatly influenced by their membrane-restricted setting. We propose that activin affinity is modulated by the ligand flexibility and that cooperativity is achieved by binding to two ActRII chains that immobilize activin in a type I binding-competent orientation.
A flexible activin explains the membrane-dependent cooperative assembly of TGF-beta family receptors.,Greenwald J, Vega ME, Allendorph GP, Fischer WH, Vale W, Choe S Mol Cell. 2004 Aug 13;15(3):485-9. PMID:15304227[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
↑ Greenwald J, Vega ME, Allendorph GP, Fischer WH, Vale W, Choe S. A flexible activin explains the membrane-dependent cooperative assembly of TGF-beta family receptors. Mol Cell. 2004 Aug 13;15(3):485-9. PMID:15304227 doi:http://dx.doi.org/10.1016/j.molcel.2004.07.011
