3MWM:
reference: Graded expression of zinc-responsive genes through two regulatory zinc-binding sites in Zur., Shin JH, Jung HJ, An YJ, Cho YB, Cha SS, Roe JH, Proc Natl Acad Sci U S A. 2011 Mar 22;108(12):5045-50. Epub 2011 Mar 7. PMID: 21383173

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