Characterization of selenoprotein P as a selenium supply protein
2002
Saito, Yoshiro | Takahashi, Kazuhiko
Selenium (Se) is well known to be essential for cell culture when using a serumâfree medium, but not when a medium containing serum is used. This finding suggests that serum contains some usable form of Se. To identify the Seâsupplier, Tâlymphoma (Jurkat) cells were cultured for 3âdays in the presence of human serum immunodepleted of Seâcontaining serum protein, selenoprotein P or extracellular glutathione peroxidase. The Seâdependent enzyme activities (glutathione peroxidases and thioredoxin reductase) and Se content within the cells markedly decreased only when cultured with selenoprotein Pâdepleted serum. Compared with other Seâcontaining proteins, the addition of purified selenoprotein P to the selenoprotein Pâdepleted serum or a serumâfree medium was the most effective for the recovery of cellular glutathione peroxidase activity (index of Se status). These results suggest that selenoprotein P functions as a Seâsupply protein, delivering Se to the cells.
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