This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'Steroids act via nuclear receptors which interact with DNA through \nSelect and explain. \nA. Helix turn helix, B. Zinc finger motif, C. Histidine, D. Leucine zipper', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Binding of transcription regulatory proteins to DNA is regulated by several motifs :\n\n\nHelix turn helix\nLeucine zipper\nZinc finger\n\n\n\nBinding motif for steroid receptor family & thyroid (nuclear) receptor family is a zinc finger.\nIn proteins with zinc - finger motif, the binding site is repeated 2-9 times.\nProteins with helix-turn-helix and leucine zipper motifs form symmetrical palindromes and their DNA binding sites are symmetrical palindromes.\n\nIn leucine - zipper motif, there is a periodic repeat of a leucine residue at every 7th\xa0position', 'role': 'assistant'}]