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. Author manuscript; available in PMC: 2009 Nov 1.
Published in final edited form as: Structure. 2008 Nov 12;16(11):1616–1625. doi: 10.1016/j.str.2008.10.002

Figure 4. A Schematic Model Explaining Why O-Mad2 Is an Autoinhibited Conformer.

Figure 4

In O-Mad2, the C-terminal β7/8 hairpin blocks the access of Cdc20 to β6. In C-Mad2, β6 is exposed and can allow edge-on interactions with he Mad2-binding motif of Cdc20. The β8’/8’’ hairpin can then detach from β5, wrap around Cdc20, and re-attach to β5. In the Mad2–Cdc20 complex, Cdc20 is trapped by Mad2, similar to the way that car passengers are restrained by seat-belts. Note that both the original β7/8 hairpin and the corresponding regions in C-Mad2 are colored green. The hydrogen-bonding networks in the β7/8 and β8’/8’’ hairpins are different from one another.