RNA-A Publication of the RNA Society 1998 Nov;4(11):1436-1443.
Overproduction of selenocysteine tRNA in Chinese hamster ovary cells following transfection of the mouse tRNA([Ser]Sec) gene.
Moustafa ME, El-Saadani MA, Kandeel KM, Mansur DB, Lee BJ, Hatfield DL, Diamond AM.
Selenocysteine insertion during selenoprotein biosynthesis begins with the aminoacylation of selenocysteine tRNA([Ser]Sec) with serine, the conversion of the serine moiety to selenocysteine, and the recognition of specific UGA codons within the mRNA. Selenocysteine tRNA([Ser]Sec) exists as two major forms, differing by methylation of the ribose portion of the nucleotide at the wobble position of the anticodon. The levels and relative distribution of these two forms of the tRNA are influenced by selenium in mammalian cells and tissues. We have generated Chinese hamster ovary cells that exhibit increased levels of tRNA([Ser]Sec) following transfection of the mouse tRNA([Ser]Sec) gene. The levels of selenocysteine tRNA([Ser]Sec) in transfectants increased proportionally to the number of stably integrated copies of the tRNA([Ser]Sec) gene. Although we were able to generate transfectants overproducing tRNA([Ser]Sec) by as much as tenfold, the additional tRNA was principally retained in the unmethylated form. Selenium supplementation could not significantly affect the relative distributions of the two major selenocysteine tRNA([Ser]Sec) isoacceptors. In addition, increased levels of tRNA([Ser]Sec) did not result in measurable alterations in the levels of selenoproteins, including glutathione peroxidase.
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