Cardiac nitric oxide synthase-1 localization within the cardiomyocyte is accompanied by the adaptor protein, CAPON

Farideh Beigi, Behzad N. Oskouei, Meizi Zheng, Carol A. Cooke, Guillaume Lamirault, Joshua M. Hare

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


The mechanism(s) regulating nitric oxide synthase-1 (NOS1) localization within the cardiac myocyte in health and disease remains unknown. Here we tested the hypothesis that the PDZ-binding domain interaction between CAPON (carboxy-terminal PDZ ligand of NOS1), a NOS1 adaptor protein and NOS1, contribute to NOS1 localization in specific organelles within cardiomyocytes. Ventricular cardiomyocytes and whole heart homogenates were isolated from sham and post-myocardial infarction (MI) wild-type (C57BL/6) and NOS1-/- female mice for quantification of CAPON protein expression levels. NOS1, CAPON, xanthine oxidoreductase and Dexras1, a CAPON binding partner, were all present and enriched in isolated cardiac sarcoplasmic reticulum (SR) fractions. CAPON co-immunoprecipitated with the mu and alpha isoforms of NOS1 in whole heart lysates, and co-localization of CAPON and NOS1 was demonstrated in the SR and mitochondria with dual immuno-gold electron microscopy. Following MI, CAPON and NOS1 both redistributed to caveolae and colocalized with caveolin-3. In addition, following MI, expression level of CAPON remained unchanged and Dexras1 was reduced, CAPON binding to xanthine oxidoreductase was augmented and the plasma membrane calcium ATPase (PMCA) increased. In NOS1 deficient myocytes, CAPON abundance in the SR was reduced, and redistribution to caveolae and PMCA binding after MI was absent. Together these findings support the hypothesis that NOS1 redistribution in injured myocardium requires the formation of a complex with the PDZ adaptor protein CAPON.

Original languageEnglish (US)
Pages (from-to)226-233
Number of pages8
JournalNitric Oxide - Biology and Chemistry
Issue number3-4
StatePublished - Dec 15 2009
Externally publishedYes


  • Dexras1
  • Heart failure
  • Nitric oxide synthase-1 (NOS1)
  • PDZ-interaction
  • PMCA

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry
  • Cancer Research
  • Physiology


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