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, N terminus
Identifiers
Symbol	SelP_N
Pfam	PF04592
Pfam clan	CL0172
InterPro	IPR007671
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

SelP, C terminus
Identifiers
Symbol	SelP_C
Pfam	PF04593
InterPro	IPR007672
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Function

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]

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.^[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

Function

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

Structure

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

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 of whole-body selenium.^[5]

Structure

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

Protein interactions

Binds to heparin in a pH-dependent manner^[2]

References

1. Mostert V (April 2000). "Selenoprotein P: properties, functions, and regulation". Arch. Biochem. Biophys. 376 (2): 433–8. doi:10.1006/abbi.2000.1735. PMID 10775431.
2. Burk RF; Hill KE (2009). "Selenoprotein P-expression, functions, and roles in mammals". Biochim Biophys Acta. 1790 (11): 1441–7. doi:10.1016/j.bbagen.2009.03.026. PMC 2763998. PMID 19345254.
3. Kryukov GV; Gladyshev VN (December 2000). "Selenium metabolism in zebrafish: multiplicity of selenoprotein genes and expression of a protein containing 17 selenocysteine residues". Genes Cells. 5 (12): 1049–60. doi:10.1046/j.1365-2443.2000.00392.x. PMID 11168591. S2CID 31432708.
4. Fujii M; Saijoh K; Kobayashi T; Fujii S; Lee MJ; Sumino K (October 1997). "Analysis of bovine selenoprotein P-like protein gene and availability of metal responsive element (MRE) located in its promoter". Gene. 199 (1–2): 211–7. doi:10.1016/S0378-1119(97)00369-7. PMID 9358058.
5. Hill KE, Zhou J, Austin LM, Motley AK, Ham AJ, Olson GE, et al. (2007). "The selenium-rich C-terminal domain of mouse selenoprotein P is necessary for the supply of selenium to brain and testis but not for the maintenance of whole body selenium". J Biol Chem. 282 (15): 10972–80. doi:10.1074/jbc.M700436200. PMID 17311913.

This article incorporates text from the public domain Pfam and InterPro: IPR007672