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Free Radic Biol Med. 2010 Sep 1;49(5):894-9. doi: 10.1016/j.freeradbiomed.2010.06.019. Epub 2010 Jun 27.

The concentration of extracellular superoxide dismutase in plasma is maintained by LRP-mediated endocytosis.

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  • 1Department of Molecular Biology, Center for Insoluble Protein Structures and Interdisciplinary Nanoscience Center, Aarhus University, DK-8000 Aarhus C, Denmark.

Abstract

In this study, we show that human extracellular superoxide dismutase (EC-SOD) binds to low-density lipoprotein receptor-related protein (LRP). This interaction is most likely responsible for the removal of EC-SOD from the blood circulation via LRP expressed in liver tissue. The receptor recognition site was located within the extracellular matrix-binding region of EC-SOD. This region encompasses the naturally occurring Arg213Gly amino acid substitution, which affects the affinity of EC-SOD for ligands in the extracellular space. Interestingly, the binding between LRP and Arg213Gly EC-SOD was significantly reduced, thus clarifying the observation that hetero- or homozygous carriers present with a significant increase in EC-SOD in their blood. On the basis of our results, we speculate that EC-SOD synthesized locally in tissues diffuses slowly into the circulation, from where it is removed by binding to LRP present in the liver. The interaction between LRP and EC-SOD is thus likely to be important for maintaining redox balance in the circulation.

Copyright 2010 Elsevier Inc. All rights reserved.

PMID:
20600835
[PubMed - indexed for MEDLINE]
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