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Review
. 2019 Nov;192(1):18-25.
doi: 10.1007/s12011-019-01827-y. Epub 2019 Jul 24.

New Directions for Understanding the Codon Redefinition Required for Selenocysteine Incorporation

Michael T Howard  1 , Paul R Copeland  2
Affiliations
Review

New Directions for Understanding the Codon Redefinition Required for Selenocysteine Incorporation

Michael T Howard et al. Biol Trace Elem Res. 2019 Nov.

Abstract

The fact that selenocysteine (Sec) is delivered to the elongating ribosome by a tRNA that recognizes a UGA stop codon makes it unique and a thorn in the side of what was originally thought to be a universal genetic code. The mechanism by which this redefinition occurs has been slowly coming to light over the past 30 years, but key questions remain. This review seeks to highlight the prominent mechanistic questions that will guide the direction of work in the near future. These questions arise from two major aspects of Sec incorporation: (1) novel functions for the Sec insertion sequence (SECIS) that resides in all selenoprotein mRNAs and (2) the myriad of RNA-binding proteins, both known and yet to be discovered, that act in concert to modify the translation elongation process to allow Sec incorporation.

Keywords: RNA-binding proteins; SECIS; Selenium; Selenocysteine.

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Figures

Figure 1.
Figure 1.
The SECIS element is comprised of distinct segments as shown. The residues shown in red are the only universally conserved features of the sequence.
Figure 2.
Figure 2.
A model for Sec incorporation that incorporates a role of nuclear SecRNP assembly in building the complex that will allow UGA recoding in the cytoplasm. SECISBP2 is designated as SBP2.
See this image and copyright information in PMC

References

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