Interaction of the endothelial nitric oxide synthase with the CAT-1 arginine transporter enhances NO by a mechanism not involving arginine transport

Chunying Li, Wei Huang, M. Brennan Harris, Jonathan M Goolsby, Richard C Venema

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


eNOS (endothelial nitric oxide synthase) catalyses the conversion of L-arginine into L-citrulline and NO. Evidence has been presented previously that eNOS is associated with the CAT (cationic amino acid transporter)-1 arginine transporter in endothelial caveolae, and it has been proposed that eNOS-CAT-1 association facilitates the delivery of extracellular L-arginine to eNOS. Definitive proof of a protein-protein interaction between eNOS and CAT-1 is lacking, however, and it is also unknown whether the two proteins interact directly or via an adaptor protein. In the present study, we raised a polyclonal antibody against CAT-1, and show using reciprocal co-immunoprecipitation protocols that eNOS and CAT-1 do indeed form a complex in BAECs (bovine aortic endothelial cells). In vitro binding assays with GST (glutathione S-transferase)-CAT-1 fusion proteins and eNOS show that the two proteins interact directly and that no single CAT-1 intracellular domain is sufficient to mediate the interaction. Overexpression of CAT-1 in BAECs by adenoviral-mediated gene transfer results in significant increases in both L-arginine uptake and NO production by the cells. However, whereas increased L-arginine transport is reversed completely by the CAT-1 inhibitor, L-lysine, increased NO release is unaltered, suggesting that NO production in this in vitro model is independent of CAT-1-mediated transport. Furthermore, eNOS enzymic activity is increased in lysates of CAT-1-overexpressing cells accompanied by increased phosphorylation of eNOS at Ser-1179 and Ser-635, and decreased association of eNOS with caveolin-1. Taken together, these data suggest that direct interaction of eNOS with CAT-1 enhances NO release by a mechanism not involving arginine transport.

Original languageEnglish (US)
Pages (from-to)567-574
Number of pages8
JournalBiochemical Journal
Issue number3
StatePublished - Mar 15 2005


  • Arginine paradox
  • Arginine transport
  • CAT-1
  • Endothelial nitric oxide synthase (eNOS)
  • Protein-protein interaction

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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