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The beta-isoform of neuronal nitric oxide synthase (nNOS) lacking the PDZ domain is localized at the sarcolemma
- Baum, Oliver, Schläppi, Simon, Huber-Abel, Felicitas A., Weichert, Alexander, Hoppeler, Hans, Zakrzewicz, Andreas
- FEBS letters 2011 v.585 no.20 pp. 3219-3223
- antibodies, epitope mapping, immunoblotting, immunohistochemistry, muscles, neuronal nitric oxide synthase, skeletal muscle
- In skeletal muscles, the expression of neuronal NO synthase (nNOS) isoforms is uncharacterized at the protein level. We therefore conducted epitope mapping with anti-peptide-antibodies. Antibodies specific for the nNOS N-terminus recognized the 160-kDa alpha-isoform. In contrast, antibodies against the middle portion or the C-terminus of nNOS bound additionally to the truncated 140-kDa beta-isoform which lacks the PDZ-domain present in the alpha-isoform. All nNOS immunohistochemical reactivity was confined to the sarcolemma. Consistently, immunoblotting disclosed both nNOS-isoforms to be co-enriched in the membrane-associated fractions. The beta-isoform was co-immunoprecipitated with alpha-isoform antibodies in muscle extracts indicating an association of both nNOS-isoforms to direct the beta-variant to the sarcolemma.