4HTT:
reference: The Glove-like Structure of the Conserved Membrane Protein TatC Provides Insight into Signal Sequence Recognition in Twin-Arginine Translocation., Ramasamy S, Abrol R, Suloway CJ, Clemons WM Jr, Structure. 2013 Apr 9. pii: S0969-2126(13)00085-3. doi:, 10.1016/j.str.2013.03.004. PMID: 23583035

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