[摘要]:Background: Selenoprotein K (SelK) is an endoplasmic reticulum (ER) protein of unknown function. Results: SelK associates with proteins involved in elimination of misfolded proteins from the ER. Conclusion: SelK is a functional component of ER homeostasis. Significance: This study defines a new family of selenoproteins and links it to an ER-associated degradation.