5VMQ:
reference: Charge neutralization in the active site of the catalytic trimer of aspartate transcarbamoylase promotes diverse structural changes., Endrizzi JA, Beernink PT, Protein Sci. 2017 Aug 19. doi: 10.1002/pro.3277. PMID: 28833948

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