Domain structure of bi-functional selenoprotein P

Yoshiro Saito, Noriko Sato, Masaki Hirashima, Gen Takebe, Shigeharu Nagasawa, Kazuhiko Takahashi

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105 Citations (Scopus)


Human selenoprotein P (SeP), a selenium-rich plasma glycoprotein, is presumed to contain ten selenocysteine residues; one of which is located at the 40th residue in the N-terminal region and the remaining nine localized in the C-terminal third part. We have shown that SeP not only catalyses the reduction of phosphatidylcholine hydroperoxide by glutathione [Saito, Hayashi, Tanaka, Watanabe, Suzuki, Saito and Takahashi (1999) J. Biol. Chem. 274, 2866-2871], but also supplies its selenium to proliferating cells [Saito and Takahashi (2002) Eur. J. Biochem. 269, 5746-5751]. Treatment of SeP with plasma kallikrein resulted in a sequential limited proteolysis (Arg-235-Gln-236 and Arg-242-Asp-243). The N-terminal (residues 1-235) and C-terminal (residues 243-361) fragments exhibited enzyme activity and selenium-supply activity respectively. These results confirm that SeP is a bi-functional protein and suggest that the first selenocysteine residue is the active site of the enzyme and the remaining nine residues function as a selenium supplier.

Original languageEnglish
Pages (from-to)841-846
Number of pages6
JournalBiochemical Journal
Issue number3
Publication statusPublished - 2004 Aug 1


  • Bi-functional protein
  • Domain structure
  • Glutathione peroxidase (GPx)
  • Plasma kallikrein
  • Selenium
  • Selenoprotein


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