Affiliations: Thyroid Division, Department of Medicine, Brigham and
Women's Hospital and Harvard Medical School, Boston, MA 02115, USA | Department of Cell Biology, Lerner Research Institute,
Cleveland Clinic Foundation, Cleveland, OH 44195, USA | Basic Research Laboratory, National Cancer Institute,
National Institutes of Health, Bethesda, MD 20892, USA
Note: [] Thyroid Division, Harvard Institutes of Medicine, 77 Avenue
Louis Pasteur, Boston, MA 02115, USA. Tel.: +1 617 525 5153; Fax: +1 617 731
4718; E-mail: [email protected]
Abstract: The mechanism of selenocysteine incorporation in eukaryotes has been
assumed for almost a decade to be inherently different from that in
prokaryotes, due to differences in the architecture of selenoprotein mRNAs in
the two kingdoms. After extensive efforts in a number of laboratories spanning
the same time frame, some of the essential differences between these mechanisms
are finally being revealed, through identification of the factors catalyzing
cotranslational selenocysteine insertion in eukaryotes. A single factor in
prokaryotes recognizes both the selenoprotein mRNA, via sequences in the coding
region, and the unique selenocysteyl-tRNA, via both its secondary structure and
amino acid. The correponding functions in eukaryotes are conferred by two
distinct but interacting factors, one recognizing the mRNA, via structures in
the 3' untranslated region, and the second recognizing the tRNA. Now, with
these factors in hand, crucial questions about the mechanistic details and
efficiency of this intriguing process can begin to be addressed.
