Document Detail

Plasma selenium-dependent glutathione peroxidase. Cell of origin and secretion.
MedLine Citation:
PMID:  2777767     Owner:  NLM     Status:  MEDLINE    
Human plasma glutathione peroxidase (GSHPx) has been shown to be a glycosylated selenoprotein distinct enzymatically, structurally, and antigenically from known cellular glutathione peroxidases. The extracellular location of the enzyme and the fact that it is glycosylated suggested that it is a secreted protein. Utilizing mutually non-cross-reactive antibodies to human cellular and plasma GSHPx, we conducted a search to determine the tissue of origin for plasma GSHPx. The cells screened were endothelial cells because they are the main source of extracellular superoxide dismutase, HL-60 cells (myeloid cell line) because they are the main source of extracellular H2O2, and Hep G2 cells (hepatic cell line) because they are the source of many plasma proteins. Human umbilical vein endothelial cells were metabolically labeled with either [35S]methionine or [75Se]selenious acid, and HL-60 cells and Hep G2 cells were metabolically labeled with [75Se]selenious acid. Proteins were immunopurified from the labeled cells and their media with either anti-red blood cell (RBC) GSHPx IgG or with anti-plasma GSHPx IgG. Utilizing anti-RBC GSHPx IgG, only the cellular form of the enzyme was precipitated from all the cells tested but not from their media. When anti-plasma GSHPx IgG was applied to the cells and their media, a selenoprotein was precipitated only from the media of Hep G2 cells. When Hep G2 cells were incubated in the presence of the carboxylic ionophore monensin, an intracellular selenoprotein could be detected using anti-plasma GSHPx IgG. The precipitation of the cellular form from all three cell types was partially inhibited by preincubation of the anti-RBC GSHPx IgG with purified RBC GSHPx while the precipitation of the selenoprotein from the medium of Hep G2 cells by anti-plasma GSHPx IgG was prevented by preincubation of the antibody with purified plasma GSHPx. We suggest that plasma GSHPx is synthesized by and secreted from hepatic cells. This is, to the best of our knowledge, the only known selenoprotein with a defined function that has been shown to be synthesized for secretion by mammalian cells.
N Avissar; J C Whitin; P Z Allen; D D Wagner; P Liegey; H J Cohen
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  264     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1989 Sep 
Date Detail:
Created Date:  1989-10-25     Completed Date:  1989-10-25     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  15850-5     Citation Subset:  IM    
Department of Pediatrics, University of Rochester School of Medicine and Dentistry, New York 14642.
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MeSH Terms
Cell Line
Electrophoresis, Polyacrylamide Gel
Endothelium, Vascular / enzymology
Erythrocytes / enzymology
Glutathione Peroxidase / blood*,  isolation & purification
Molecular Weight
Selenious Acid
Selenium / pharmacology*
Grant Support
Reg. No./Substance:
7782-49-2/Selenium; 7783-00-8/Selenious Acid; EC Peroxidase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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