2OTB:
reference: Structural basis for reversible photobleaching of a green fluorescent protein homologue., Henderson JN, Ai HW, Campbell RE, Remington SJ, Proc Natl Acad Sci U S A. 2007 Apr 17;104(16):6672-7. Epub 2007 Apr 9. PMID: 17420458

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