Protein Domain : Selenophosphate synthetase, class I IPR023061

Type	Family
Description	The UGA (TGA) codon is normally a termination codon, however it is also used as a selenocysteine (Sec) codon by numerous organisms [ ]. 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 [, ]. SPS catalyses the production of the selenium donor compound monoselenophosphate (MSP) from selenide and ATP. MSP is then used to synthesize Sec from seryl-tRNAs []. SPS was initially identified in E. coli as the product of the gene selD, one of four essential selenoprotein synthesis genes (selA-D) [, ]. 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 type I SPS, mostly from bacteria.
Short Name	SelD_I