Selenoprotein P
{{Infobox protein family
| Symbol = SelP_N
| Name = SelP, N terminus
| image =
| width =
| caption =
| Pfam = PF04592
| Pfam_clan = CL0172
| InterPro = IPR007671
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{Infobox protein family
| Symbol = SelP_C
| Name = SelP, C terminus
| image =
| width =
| caption =
| Pfam = PF04593
| Pfam_clan =
| InterPro = IPR007672
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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.{{cite journal | author = Mostert V | title = Selenoprotein P: properties, functions, and regulation | journal = Arch. Biochem. Biophys. | volume = 376 | issue = 2 | pages = 433–8 |date=April 2000 | pmid = 10775431 | doi = 10.1006/abbi.2000.1735 }} This particular protein contains two domains: the C terminal and N terminal domain. The N-terminal domain is larger than the C terminal{{cite journal|author1=Burk RF |author2=Hill KE | title=Selenoprotein P-expression, functions, and roles in mammals. | journal=Biochim Biophys Acta | year= 2009 | volume= 1790 | issue= 11 | pages= 1441–7 | pmid=19345254 | doi=10.1016/j.bbagen.2009.03.026 | pmc=2763998 }} and the N-terminal is thought to be glycosylated.{{cite journal |author1=Kryukov GV |author2=Gladyshev VN | title = Selenium metabolism in zebrafish: multiplicity of selenoprotein genes and expression of a protein containing 17 selenocysteine residues | journal = Genes Cells | volume = 5 | issue = 12 | pages = 1049–60 |date=December 2000 | pmid = 11168591 | doi = 10.1046/j.1365-2443.2000.00392.x|s2cid=31432708 | doi-access = free }} The human version is SEPP1.
Function
SelP may have antioxidant properties. It can attach to epithelial cells, and may protect vascular endothelial cells against peroxynitrite toxicity. The high selenium content of SelP suggests that it may be involved in selenium intercellular transport or storage. The promoter structure of bovine SelP suggests that it may be involved in countering heavy metal intoxication, and may also have a developmental function.{{cite journal |author1=Fujii M |author2=Saijoh K |author3=Kobayashi T |author4=Fujii S |author5=Lee MJ |author6=Sumino K | title = Analysis of bovine selenoprotein P-like protein gene and availability of metal responsive element (MRE) located in its promoter | journal = Gene | volume = 199 | issue = 1–2 | pages = 211–7 |date=October 1997 | pmid = 9358058 | doi = 10.1016/S0378-1119(97)00369-7}}
Structure
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. 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.
N terminal domain
=Function=
N-terminal domain allows conservation of whole body selenium
=Structure=
The structure of the N-terminal domain is larger and contains less Selenium. However it is thought to be heavily glycosylated.
C terminal domain
=Function=
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