The family of steroid receptor proteins contains relatively small domains with just under 70 amino acids and 9 conserved cysteine residues. The cystein residues in two units are coordinated around corresponding Zn2+ ions. The metal in these subunits has [Zn(Cys)4] coordination.

Although the steroid receptor proteins are bound to DNA, they are unimportant for DNA recognition. Rather, they mediate the dimerisation of the protein.


  Coordination of the Zn2+ ions in the subunits