Nitric oxide synthase 1 PDZ domain (nNOS-PDZ)

The Nitric oxide synthase 1 (nNOS) PDZ domain is a specialized protein-interaction module located at the N-terminus of the neuronal nitric oxide synthase enzyme (UniProt P29475). It is structurally unique among PDZ domains due to an additional beta-finger motif that allows it to engage in heterodimeric interactions with other PDZ domains, most notably the second PDZ domain of Postsynaptic density protein 95 (PSD-95) (PubMed: 10818112). This interaction is essential for the spatial coupling of nNOS to the N-methyl-D-aspartate (NMDA) receptor, ensuring that calcium influx through the receptor leads to localized nitric oxide (NO) production (PubMed: 10541237). In pathological states like ischemic stroke and chronic pain, overactivation of this pathway leads to excitotoxic levels of NO and subsequent neuronal death (PubMed: 20724630). Therapeutic strategies targeting the nNOS-PDZ domain aim to disrupt its interaction with PSD-95 or other adaptors like NOS1AP (CAPON) using small molecules such as ZL006 and IC87201 or peptide-based inhibitors (PubMed: 25591494). By uncoupling nNOS from the NMDA receptor complex, these inhibitors provide neuroprotection and analgesic effects without the adverse side effects typically associated with direct NMDA receptor antagonism or global nNOS enzyme inhibition (PubMed: 26179431). However, the exact binding site and specificity of some small-molecule inhibitors remain a subject of scientific debate (PubMed: 26179431).

Other names

Neuronal nitric oxide synthase PDZ domainNOS1 PDZ domainnNOS N-terminal PDZ domainnNOS-PSD-95 interaction site

Inhibition of protein-protein interaction (PPI) between the nNOS PDZ domain and scaffolding proteins such as PSD-95 or NOS1AP.