In molecular biology, the protein domain selenoprotein P (SelP) is the only known eukaryotic selenoprotein that contains multiple selenocysteine (Sec) residues. It is a secreted glycoprotein, often found in the plasma. Its precise function remains to be elucidated; however, it is thought to have antioxidant properties.[1] This particular protein contains two domains: the C terminal and N terminal domain. The N-terminal domain is larger than the C terminal[2] and the N-terminal is thought to be glycosylated.[3]