2ok5

OverviewOverview

Factor B is the central protease of the complement system of immune, defense. Here, we present the crystal structure of human factor B at 2.3-A, resolution, which reveals how the five-domain proenzyme is kept securely, inactive. The canonical activation helix of the Von Willebrand factor A, (VWA) domain is displaced by a helix from the preceding domain linker. The, two helices conformationally link the scissile-activation peptide and the, metal ion-dependent adhesion site required for binding of the ligand C3b., The data suggest that C3b binding displaces the three N-terminal control, domains and reshuffles the two central helices. Reshuffling of the helices, releases the scissile bond for final proteolytic activation and generates, a new interface between the VWA domain and the serine protease domain., This allosteric mechanism is crucial for tight regulation of the, complement-amplification step in the immune response.

About this StructureAbout this Structure

2OK5 is a Single protein structure of sequence from Homo sapiens with and as ligands. Active as Alternative-complement-pathway C3/C5 convertase, with EC number 3.4.21.47 Full crystallographic information is available from OCA.

ReferenceReference

Factor B structure provides insights into activation of the central protease of the complement system., Milder FJ, Gomes L, Schouten A, Janssen BJ, Huizinga EG, Romijn RA, Hemrika W, Roos A, Daha MR, Gros P, Nat Struct Mol Biol. 2007 Mar;14(3):224-8. Epub 2007 Feb 25. PMID:17310251

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