In support of our hypothesis, cis-azobenzene was modelled into the E2(AzTG-4) and E2(AzTG-6) structures, indicating that, while both cis-AzTG-4 and cis-AzTG-6 are able to be accommodated, greater restriction is imposed upon the photoswitch group of cis-AzTG-4. In the case of cis-AzTG-4, the distal phenyl group likely sits in a small cavity formed by Leu253, Leu311, and Pro312, while for cis-AzTG-6, it sits in a larger cavity formed by Leu61, Leu253, and Pro312 (Figure ).