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The PDZ domains in the structure of the neural enzyme neuronal nitric oxide synthase are also present in two of its protein substrates, postsynaptic density protein 95 and 93 (PSD-95 and PSD-93). The PDZ domains of nNOS and PDS-95 interact so that nNOS can bind with syntrophin in the sarcolemma. The absence of PDZ domains in mutant mice nNOS prevents them from binding with PDZ, and points to the way nNOS is targeted towards membrane structures.

Dystrophin, the protein mutated in Duchenne muscular dystrophyin, is active in detaching neuronal-type nitric oxide synthase (nNOS) to skeletal muscle sarcolemma. The dystrophin complex interacts with an N-terminal domain of nNOS consisting of a GLGF motif. The abnormal nNOS regulation may help in the preferential degeneration of fast-twitch muscle fibers in DMD.