| Symbol: | SelP_N |
| SelP, N terminus | |
| Pfam: | PF04592 |
| Pfam Clan: | CL0172 |
| Interpro: | IPR007671 |
| Symbol: | SelP_C |
| SelP, C terminus | |
| Pfam: | PF04593 |
| Interpro: | IPR007672 |
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 seleniumand 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 maintenanceof whole-body selenium.[5]
The C-terminal domain is smaller in size but far more rich in selenium.[5]
Binds to heparin in a pH-dependent manner[2]