2HUG:
reference: Assembly of chloroplast signal recognition particle involves structural rearrangement in cpSRP43., Kathir KM, Rajalingam D, Sivaraja V, Kight A, Goforth RL, Yu C, Henry R, Kumar TK, J Mol Biol. 2008 Aug 1;381(1):49-60. Epub 2008 Jun 3. PMID: 18586266

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