Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Subscribe

Sci. Signal., 4 January 2011
Vol. 4, Issue 154, p. ec7
[DOI: 10.1126/scisignal.4154ec7]

EDITORS' CHOICE

Structural Biology A Safety Catch on Immune Response

Valda Vinson

Science, AAAS, Washington, DC 20005, USA

The complement system is an integral part of the innate immune system. When triggered, it initiates a cascade that marks intruders for elimination and stimulates immune responses. The key amplification step is cleavage of a complex comprising the complement fragment C3b and factor B (C3bB) by factor D (FD). Forneris et al. now describe the crystal structure of C3bB and its complex with FD. The structures support a mechanism in which membrane-bound C3b stabilizes an open form of factor B (FB) that has its scissile bond accessible. FD binds through a site distant from its catalytic center to the open form of FB, which activates FD. The two conformational equilibria represent a double safety-catch that would allow tight regulation of this immune response pathway.

F. Forneris, D. Ricklin, J. Wu, A. Tzekou, R. S. Wallace, J. D. Lambris, P. Gros, Structures of C3b in complex with factors B and D give insight into complement convertase formation. Science 330, 1816–1820 (2010). [Abstract] [Full Text]

Citation: V. Vinson, A Safety Catch on Immune Response. Sci. Signal. 4, ec7 (2011).



To Advertise     Find Products


Science Signaling. ISSN 1937-9145 (online), 1945-0877 (print). Pre-2008: Science's STKE. ISSN 1525-8882