Exon structure of cardiac muscle expressed nNOS splice variants and their expression profile in the nNOS null mouse models used in this study.

Abstract

<p>Coding exons of each splice variant are gray numbered boxes. Exon 2 encodes the PDZ (PSD95/Dlg1/ZO1) protein-protein interaction domain. Exon 6 encodes the heme binding domain essential for nitric oxide synthesis. Exon sequences that form unique 5’ untranslated sequences are white. Asterisks mark translation initiation sites. nNOS splice variant expression in control and murine KN1 and KN2 nNOS knockout models are shown on the right. A tick mark indicates expression. A cross mark indicates absence of expression and/or activity. This study employs two nNOS knockout models: first knockout of nNOS (KN1, exon 2 deletion) and second knockout of nNOS (KN2, exon 6 deletion). KN1 and KN2 mice have distinct isoform expression profiles. KN1 mice lack nNOSα and nNOSμ, but still express nNOSβ. KN2 mice do not express any active nNOS splice variants.</p