Selenophosphate synthetase 2

SEPHS2
Identifiers
Aliases	SEPHS2, SPS2, SPS2b, selenophosphate synthetase 2
External IDs	OMIM: 606218; MGI: 108388; GeneCards: SEPHS2
Enzyme activity
Gene location (Human)
Chr.	Chromosome 16 (human)
End	30,445,874 bp
Gene location (Mouse)
Chr.	Chromosome 7 (mouse)
End	126,873,227 bp
RNA expression pattern
	Top expressed in
	jejunal mucosa; ; kidney tubule; ; right lobe of liver; ; renal medulla; ; duodenum; ; human kidney; ; mucosa of colon; ; glomerulus; ; mucosa of sigmoid colon; ; secondary oocyte;
	Top expressed in
	left lobe of liver; ; spermatocyte; ; right kidney; ; granulocyte; ; spermatid; ; renal corpuscle; ; Paneth cell; ; jejunum; ; human kidney; ; crypt of lieberkuhn of small intestine;
	More reference expression data
	n/a
Gene ontology
Molecular function	transferase activity; nucleotide binding; ATP binding; kinase activity; selenide, water dikinase activity;
Cellular component	cytosol; cellular component; cytoplasm;
Biological process	phosphorylation; selenium compound metabolic process; selenocysteine biosynthetic process; selenocysteine metabolic process; tRNA seleno-modification;
	Sources:Amigo / QuickGO
Orthologs
Databases	NCBI: entry; OMA: entry
	22928
	20768
	ENSG00000179918
	ENSMUSG00000049091
	Q99611
	P97364
	NM_012248
	NM_009266
	NP_036380
	NP_033292
	Wikidata
View/Edit Human	View/Edit Mouse

Selenophosphate synthetase 2, also called Selenide, water dikinase 2, is an enzyme that in humans is encoded by the SEPHS2 gene. SEPHS2 is a selenoprotein that functions to produce selenophosphate which is needed in selenoprotein synthesis. It has a paralog, SEPHS1, which may also fulfill this role, but some more recent studies have cast doubt on SEPHS1's role in selenoprotein synthesis.

Function

Selenoproteins are a rare type of protein which incorporate the non-standard amino acid selenocysteine, which contains the element selenium. In eukaryotes and archaea, selenocysteine is produced from (tRNA-bound) serine through a two step process, where it is first phosphorylated by L-seryl-tRNA(Sec) kinase (EC 2.7.1.164), and then converted to selenocysteine by the enzyme SepSecS (EC 2.9.1.2). This second reaction requires selenophosphate, which is produced by selenide, water dikinases (EC 2.7.9.3), and in particular SEPHS2, which catalyzes the reaction:

ATP + selenide + H₂O = AMP + selenophosphate + phosphate

It is predicted to form a protein complex with SEPHS1, SepSecS, and TRNAU1AP. SEPHS2 has not yet been associated with any human diseases, but knock-out of the Sephs2 gene is lethal in mice during embryonic development.

References

1 2 3 GRCh38: Ensembl release 89: ENSG00000179918 – Ensembl, May 2017
1 2 3 GRCm38: Ensembl release 89: ENSMUSG00000049091 – Ensembl, May 2017
↑ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
↑ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
1 2 3 "Selenide, water dikinase 2". uniprot.org. UniProt consortium. Retrieved 2026-10-15.
↑ "Zincore component SEPHS1". uniprot.org. UniProt consortium. Retrieved 2026-10-15.
1 2 Minich WB (January 2022). "Selenium metabolism and biosynthesis of selenoproteins in the human body" (PDF). Biochemistry (Moscow). 87(Suppl 1): S168-77. doi:10.1134/S0006297922140139.
↑ EC 2.7.9.3
↑ "Sephs2; selenophosphate synthetase 2". IMPC. Retrieved 2026-10-15.

This article on a gene on human chromosome 16 is a stub. You can help Wikipedia by adding missing information.

[refGRCh38Ensembl-1] 1 2 3 GRCh38: Ensembl release 89: ENSG00000179918 – Ensembl, May 2017

[refGRCm38Ensembl-2] 1 2 3 GRCm38: Ensembl release 89: ENSMUSG00000049091 – Ensembl, May 2017

[3] "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.

[4] "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.

[uniprot-5] 1 2 3 "Selenide, water dikinase 2". uniprot.org. UniProt consortium. Retrieved 2026-10-15.

[6] "Zincore component SEPHS1". uniprot.org. UniProt consortium. Retrieved 2026-10-15.

[Minich2022-7] 1 2 Minich WB (January 2022). "Selenium metabolism and biosynthesis of selenoproteins in the human body" (PDF). Biochemistry (Moscow). 87(Suppl 1): S168-77. doi:10.1134/S0006297922140139.

[8] EC 2.7.9.3

[9] "Sephs2; selenophosphate synthetase 2". IMPC. Retrieved 2026-10-15.