In biology, the PYLIS downstream sequence (PYLIS: ''pyrrolysine insertion sequence'') is a
stem-loop structure that appears on some
mRNA
In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of synthesizing a protein.
mRNA is created during the ...
sequences. This
structural motif was previously thought to cause the UAG (amber)
stop codon
In molecular biology (specifically protein biosynthesis), a stop codon (or termination codon) is a codon (nucleotide triplet within messenger RNA) that signals the termination of the translation process of the current protein. Most codons in mess ...
to be translated to the
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...
pyrrolysine instead of ending the protein translation.
However, it has been shown that PYLIS has no effect upon the efficiency of the UAG suppression,
hence even its name is, in fact, incorrect.
See also
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SECIS element
In biology, the SECIS element (SECIS: ''selenocysteine insertion sequence'') is an RNA element around 60 nucleotides in length that adopts a stem-loop structure. This structural motif (pattern of nucleotides) directs the cell to translate UGA ...
References
Further reading
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External links
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Cis-regulatory RNA elements
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