title: Update on selenoprotein biosynthesis.
abstract: CONCLUSIONS
  Selenium is an essential trace element that is incorporated in the small but vital family of proteins, namely the selenoproteins, as the selenocysteine amino acid residue. In humans, 25 selenoprotein genes have been characterized. The most remarkable trait of selenoprotein biosynthesis is the cotranslational insertion of selenocysteine by the recoding of a UGA codon, normally decoded as a stop signal.
  
  
  BACKGROUND
  In eukaryotes, a set of dedicated cis- and trans-acting factors have been identified as well as a variety of regulatory mechanisms, factors, or elements that control the selenoprotein expression at the level of the UGA-selenocysteine recoding process, offering a fascinating playground in the field of translational control. It appeared that the central players are two RNA molecules: the selenocysteine insertion sequence (SECIS) element within selenoprotein mRNA and the selenocysteine-tRNA([Ser]Sec); and their interacting partners.
  
  
  RESULTS
  After a couple of decades, despite many advances in the field and the discovery of many essential and regulatory components, the precise mechanism of UGA-selenocysteine recoding remains elusive and more complex than anticipated, with many layers of control. This review offers an update of selenoproteome biosynthesis and regulation in eukaryotes.
  
  
  CONCLUSIONS
  The regulation of selenoproteins in response to a variety of pathophysiological conditions and cellular stressors, including selenium levels, oxidative stress, replicative senescence, or cancer, awaits further detailed investigation. Clearly, the efficiency of UGA-selenocysteine recoding is the limiting stage of selenoprotein synthesis. The sequence of events leading Sec-tRNA([Ser]Sec) delivery to ribosomal A site awaits further analysis, notably at the level of a three-dimensional structure.
authors.affiliation: Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM , CNRS/UPPA, UMR5254, Pau, France .
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Bulteau
authors.affiliation: Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM , CNRS/UPPA, UMR5254, Pau, France .
authors.forename: Laurent
authors.initials: L
authors.lastname: Chavatte
mesh_terms: D018388:Codon, Terminator / Q000378:metabolism; D006801:Humans; D014176:Protein Biosynthesis; D020543:Proteome / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D012345:RNA, Transfer, Amino Acid-Specific / Q000378:metabolism; D012643:Selenium / Q000378:metabolism; D051140:Selenoproteins / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D018388:Codon, Terminator; D020543:Proteome; D012333:RNA, Messenger; D012345:RNA, Transfer, Amino Acid-Specific; D051140:Selenoproteins; C036928:tRNA, selenocysteine-; D012643:Selenium