There is one additional point perhaps worth making: As already noted in the thread, if you have a NCS homo-oligomer, the different copies in general have different environment, and proper inspection of the contacts reveals the details. On multiple occasions during inspections and review I have noticed that such is not always interpreted or welcome as a functionally necessary manifestation of the plasticity of the protein in question. In case of binding sites, in contrast it occurs that the 'best' one where a ligand actually exists or assumes a pose/environment perceived as useful for the proposed hypothesis is picked as the representative (figure), and from there the story evolves. This misses the point, and somewhat reeks of confirmation bias (the neglect of negative or 'unsuitable' results) leading straight down the road to scientific serfdom in terms of becoming a slave of one's own (pre)conceptions....
Best regards, BR