PROSITE documentation PDOC00396

Glutathione peroxidase (EC 1.11.1.9) (GSHPx) [1,2] is an enzyme that catalyzes the reduction of hydroxyperoxides by glutathione. Its main function is to protect against the damaging effect of endogenously formed hydroxyperoxides.

In higher vertebrates at least four forms of GSHPx are known to exist: a ubiquitous cytosolic form (GSHPx-1), a gastrointestinal cytosolic for (GSHPx-GI) [3], a plasma secreted form (GSHPx-P) [4], and a epididymal secretory form (GSHPx-EP). In addition to these characterized forms, the sequence of a protein of unknown function [5] has been shown to be evolutionary related to those of GSHPx's.

In filarial nematode parasites such as Brugia pahangi the major soluble cuticular protein, known as gp29, is a secreted GSHPx which could provide a mechanism of resistance to the immune reaction of the mammalian host by neutralizing the products of the oxidative burst of leukocytes [6].

Escherichia coli protein btuE, a periplasmic protein involved in the transport of vitamin B12, is also evolutionary related to GSHPx's; the significance of this relationship is not yet clear.

The catalyic site of GSHPx contains a conserved residue which is either a cysteine or, in many eukaryotic GSHPx, a selenocysteine [7]. The region around this active site residue can be used as a signature pattern. As a second signature for this family of proteins we selected a highly conserved octapeptide located in the central section of these proteins. We also developed a profile that covers the whole conserved region.

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1	Authors	Mannervik B.
	Title	Glutathione peroxidase.
	Source	Methods Enzymol. 113:490-495(1985).
	PubMed ID	4088069

2	Authors	Mullenbach G.T., Tabrizi A., Irvine B.D., Bell G.I., Tainer J.A., Hallewell R.A.
	Title	Selenocysteine's mechanism of incorporation and evolution revealed in cDNAs of three glutathione peroxidases.
	Source	Protein Eng. 2:239-246(1988).
	PubMed ID	2976939

3	Authors	Chu F.F., Doroshow J.H., Esworthy R.S.
	Title	Expression, characterization, and tissue distribution of a new cellular selenium-dependent glutathione peroxidase, GSHPx-GI.
	Source	J. Biol. Chem. 268:2571-2576(1993).
	PubMed ID	8428933

4	Authors	Takahashi K., Akasaka M., Yamamoto Y., Kobayashi C., Mizoguchi J., Koyama J.
	Title	Primary structure of human plasma glutathione peroxidase deduced from cDNA sequences.
	Source	J. Biochem. 108:145-148(1990).
	PubMed ID	2229017

5	Authors	Dunn D.K., Howells D.D., Richardson J.P., Goldfarb P.S.
	Title	A human cDNA sequence for a novel glutathione peroxidase-related selenopeptide, GPRP.
	Source	Nucleic Acids Res. 17:6390-6390(1989).
	PubMed ID	2771650

Glutathione peroxidases signatures and profile

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6	Authors	Cookson E., Blaxter M.L., Selkirk M.E.
	Title	Identification of the major soluble cuticular glycoprotein of lymphatic filarial nematode parasites (gp29) as a secretory homolog of glutathione peroxidase.
	Source	Proc. Natl. Acad. Sci. U.S.A. 89:5837-5841(1992).
	PubMed ID	1631065

7	Authors	Stadtman T.C.
	Title	Selenium biochemistry.
	Source	Annu. Rev. Biochem. 59:111-127(1990).
	PubMed ID	2142875
	DOI	10.1146/annurev.bi.59.070190.000551