1HCQ:
reference: The crystal structure of the estrogen receptor DNA-binding domain bound to DNA: how receptors discriminate between their response elements., Schwabe JW, Chapman L, Finch JT, Rhodes D, Cell 1993 Nov 5;75(3):567-78. PMID: 8221895

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).