2C9I:
reference: Chromophore-protein interactions in the anthozoan green fluorescent protein asFP499., Nienhaus K, Renzi F, Vallone B, Wiedenmann J, Nienhaus GU, Biophys J. 2006 Dec 1;91(11):4210-20. Epub 2006 Sep 15. PMID: 16980366

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