6BTM:
reference: Structure of the alternative complex III in a supercomplex with cytochrome oxidase., Sun C, Benlekbir S, Venkatakrishnan P, Wang Y, Hong S, Hosler J, Tajkhorshid E, Rubinstein JL, Gennis RB, Nature. 2018 May;557(7703):123-126. doi: 10.1038/s41586-018-0061-y. Epub 2018 Apr, 25. PMID: 29695868

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