4GIG:
reference: Conserved threonine spring-loads precursor for intein splicing., Dearden AK, Callahan B, Van Roey P, Li Z, Kumar U, Belfort M, Nayak SK, Protein Sci. 2013 Feb 19. doi: 10.1002/pro.2236. PMID: 23423655

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