Selenophosphate synthetase, class I (IPR023061)

Short name: SelD_I

Overlapping homologous superfamilies

Family relationships


The UGA (TGA) codon is normally a termination codon, however it is also used as a selenocysteine (Sec) codon by numerous organisms [PMID: 8811175]. Sec is the 21st amino acid that is inserted into selenoproteins (protein that includes a selenocysteine (Se-Cys) amino acid residue). The synthesis of Sec and its incorporation into proteins requires the activity of a number of proteins, one of which is selenophosphate synthetase (SPS), also known as the SelD gene product [PMID: 8986768, PMID: 2405383]. SPS catalises the production of the selenium donor compound monoselenophosphate (MSP) from selenide and ATP. MSP is then used to synthesize Sec from seryl-tRNAs [PMID: 2142875].

SPS was initially identified in E. coli as the product of the gene selD, one of four essential selenoprotein synthesis genes (selA-D) [PMID: 2405383, PMID: 1557403]. SelC is the tRNA itself, SelD acts as a donor of reduced selenium, SelA modifies a serine residue on SelC into selenocysteine, and SelB is a selenocysteine-specific translation elongation factor. 3' or 5' non-coding elements of mRNA have been found as probable structures for directing selenocysteine incorporation.

This entry represents the typeI SPS, mostly from bacteria.

GO terms

Biological Process

GO:0016260 selenocysteine biosynthetic process

Molecular Function

GO:0005524 ATP binding
GO:0004756 selenide, water dikinase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.