The Mad2 spindle checkpoint protein has two distinct natively folded states.
Luo, X., Tang, Z., Xia, G., Wassmann, K., Matsumoto, T., Rizo, J., Yu, H.(2004) Nat Struct Mol Biol 11: 338-345
- PubMed: 15024386 
- DOI: 10.1038/nsmb748
- Primary Citation of Related Structures:  
1S2H - PubMed Abstract: 
The spindle checkpoint delays chromosome segregation in response to misaligned sister chromatids during mitosis, thus ensuring the fidelity of chromosome inheritance. Through binding to Cdc20, the Mad2 spindle checkpoint protein inhibits the target of this checkpoint, the ubiquitin protein ligase APC/C(Cdc20) ...