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Updated: Aug 1, 2026

Preparation of Synaptic Plasma Membrane and Postsynaptic Density Proteins Using a Discontinuous Sucrose Gradient
Published on: September 3, 2014
CAPON: a protein associated with neuronal nitric oxide synthase that regulates its interactions with PSD95
S R Jaffrey1, A M Snowman, M J Eliasson
1The Johns Hopkins University School of Medicine, Department of Neuroscience, Pharmacology and Molecular Sciences, Baltimore, Maryland 21205, USA.
Abstract:
Nitric oxide (NO) produced by neuronal nitric oxide synthase (nNOS) is important for N-methyl-D-aspartate (NMDA) receptor-dependent neurotransmitter release, neurotoxicity, and cyclic GMP elevations. The coupling of NMDA receptor-mediated calcium influx and nNOS activation is postulated to be due to a physical coupling of the receptor and the enzyme by an intermediary adaptor protein, PSD95, through a unique PDZ-PDZ domain interaction between PSD95 and nNOS. Here, we report the identification of a novel nNOS-associated protein, CAPON, which is highly enriched in brain and has numerous colocalizations with nNOS. CAPON interacts with the nNOS PDZ domain through its C terminus. CAPON competes with PSD95 for interaction with nNOS, and overexpression of CAPON results in a loss of PSD95/nNOS complexes in transfected cells. CAPON may influence nNOS by regulating its ability to associate with PSD95/NMDA receptor complexes.
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