Evaluation of the Effects of G4 Ligands on the Interaction Between G-quadruplexes and Their Binding Proteins.

G-quadruplexes (G4s) regulate multiple biological processes by interacting with G4-binding proteins (G4BPs). We developed a sandwich ELISA system to evaluate G4 ligand effects on G4-G4BP binding. G4 ligands strongly affect G-quartet-protein interactions, demonstrating that high binding affinity of G4 ligands for G4s does not guarantee ternary complex formation with G4BPs.