4PBP:
reference: Crystal structures for short-chain pentraxin from zebrafish demonstrate a cyclic trimer with new recognition and effector faces., Chen R, Qi J, Yuan H, Wu Y, Hu W, Xia C, J Struct Biol. 2015 Mar;189(3):259-68. doi: 10.1016/j.jsb.2015.01.001. Epub 2015 , Jan 13. PMID: 25592778

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