Another allele called 'S3' locks PrP in a compact conformation that can bind only one copper ion per OR, corresponding to component 3 metal-binding geometry (the intermediate conformation component 2 was not modelled in our studies).
Qin and colleagues [ 2]provide data that clearly illustrate that the binding sites have multiple pre-existing conformations that can select the partner.
Allosteric effects are the outcome of dynamically shifting populations; thus binding to even slightly different DNA sequences will lead to different transcription factor conformations that can be reflected in the binding sites to their co-regulators.
Firstly, these biopolymers can occur in multiple conformations that can have distinct functionality, with the predominant conformer depending on the molecule's environment, for instance, the presence of a particular binding partner (12 16).
The slight difference may be due to the fact that PXR has a relatively large and flexible ligand-binding pocket that can accommodate ligands of different sizes and even a single ligand with different conformations.
More typically, the ligand may bind and stabilize only a subset of the many conformations sampled by its dynamic receptor, causing the population of all possible conformations to shift towards those that can best accommodate binding [ 4- 7].
The inherent flexibility of the two termini suggests that the protein has a malleable interface that can allow the binding of several partners or adopt different conformations, as manifested by its high binding capability.
However, protein-protein interactions often involve highly flexible elements that can assume many distinct conformations upon binding to different partners.
HMGB1 showed preferential binding for junction substrates J1/2 and J4/5, junctions that can interchange between fully paired and two-unpaired base conformations.
The affinities of antibodies are improved by somatic mutations that can stabilize and fix the free paratope conformations for antigen binding thereby reducing the entropic penalty upon binding [47], [48].
