The interaction between PSD-95 and Ca2+/calmodulin is enhanced by PDZ-binding proteins

In this study, we evaluate the interaction between the postsynaptic scaffolding protein, PSD-95, and calmodulin. Surface plasmon resonance spectroscopy was used to characterize the binding of PSD-95 to calmodulin that had been immobilized on a sensor chip. Additionally, soluble calmodulin was found to inhibit the binding of PSD-95 to immobilized calmodulin. The HOOK region of PSD-95, which is located between the src homology 3 domain and the guanylate kinase-like domain, was determined to be involved in the binding of PSD-95 to calmodulin. We also found that C-terminal peptides from proteins such as CRIPT and the N-methyl-d-aspartate receptor NR2B subunit, which associate with the PDZ domain of PSD-95, enhanced the affinity of PSD-95 for calmodulin. The binding of ligands to the PDZ domain may change the conformation of PSD-95 and affect the interaction between PSD-95 and calmodulin.