1QP5:
reference: Base-pairing shift in the major groove of (CA)n tracts by B-DNA crystal structures., Timsit Y, Vilbois E, Moras D, Nature 1991 Nov 14;354(6349):167-70. PMID: 1944598

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