Steroids act via nuclear receptors which interact with DNA through
Helix turn helix
Zinc finger motif
Histidine
Leucine zipper
Binding of transcription regulatory proteins to DNA is regulated by several motifs :


Helix turn helix
Leucine zipper
Zinc finger



Binding motif for steroid receptor family & thyroid (nuclear) receptor family is a zinc finger.
In proteins with zinc - finger motif, the binding site is repeated 2-9 times.
Proteins with helix-turn-helix and leucine zipper motifs form symmetrical palindromes and their DNA binding sites are symmetrical palindromes.

In leucine - zipper motif, there is a periodic repeat of a leucine residue at every 7th position