The Mu repressor-DNA complex contains an immobilized 'wing' within the minor groove.
Wojciak, J.M., Iwahara, J., Clubb, R.T.(2001) Nat Struct Biol 8: 84-90
- PubMed: 11135677 
- DOI: 10.1038/83103
- Primary Citation of Related Structures:  
1G4D - PubMed Abstract: 
We have determined the solution structure of the complex between the 'winged-helix' enhancer binding domain of the Mu repressor protein and its cognate DNA site. The structure reveals an unusual use for the 'wing' which becomes immobilized upon DNA binding where it makes intermolecular hydrogen bond contacts deep within the minor groove ...