Anti-CRIPT monoclonal antibody Made to order

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.

CRIPT, the cysteine-rich PDZ-binding protein, binds to the third PDZ domain of PSD-95 (postsynaptic density protein 95) family proteins and directly binds microtubules, linking PSD-95 family proteins to the neuronal cytoskeleton. Here, we show that overexpression of a full-length CRIPT leads to a modest decrease, and knockdown of CRIPT leads to an increase in dendritic branching in cultured rat hippocampal neurons. Overexpression of truncated CRIPT lacking the PDZ domain-binding motif, which does not bind to PSD-95, significantly decreases dendritic arborization. Conversely, overexpression of a full-length CRIPT significantly increases the number of immature and mature dendritic spines, and this effect is not observed when CRIPT increment PDZ is overexpressed. Competitive inhibition of CRIPT binding to the third PDZ domain of PSD-95 with PDZ3-binding peptides resulted in differential effects on dendritic arborization based on the origin of respective peptide sequence. These results highlight multifunctional roles of CRIPT during development and underscore the significance of the interaction between CRIPT and the third PDZ domain of PSD-95.