Selenoprotein P

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]

SelP may have antioxidant properties. It can attach to epithelial cells, and may protect vascular endothelial cells against peroxynitrite toxicity.^[1] The high selenium content of SelP suggests that it may be involved in selenium intercellular transport or storage.^[3] The promoter structure of bovine SelP suggests that it may be involved in countering heavy metal intoxication, and may also have a developmental function.^[4]

The N-terminal region always contains one Sec residue, and this is separated from the C-terminal region (9-16 Sec residues) by a histidine-rich sequence.^[3] The large number of Sec residues in the C-terminal portion of SelP suggests that it may be involved in selenium transport or storage. However, it is also possible that this region has a redox function.^[3]

N-terminal domain allows conservation of whole body selenium and appears to supply selenium to the kidney^[5]

The structure of the N-terminal domain is larger and contains less Selenium. However it is thought to be heavily glycosylated^[5]

The function of the C-terminal domain is known to be vital for maintaining levels of selenium in brain and testis tissue but not for the maintenance of whole-body selenium.^[5]

The C-terminal domain is smaller in size but far more rich in selenium.^[5]

pH依存的にヘパリンに結合する^[2]