6HRN:
reference: Crystal structure of phycocyanin from heterocyst-forming filamentous cyanobacterium Nostoc sp. WR13., Patel HM, Roszak AW, Madamwar D, Cogdell RJ, Int J Biol Macromol. 2019 May 20;135:62-68. doi: 10.1016/j.ijbiomac.2019.05.099. PMID: 31121226

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