PYLIS downstream sequence

Pyrrolysine insertion sequence 1
Predicted secondary structure of PYLIS 1 RNA.
Identifiers
Symbol	PYLIS 1
Rfam	RF01982
Other data
RNA type	Cis-regulatory element
Domain(s)	Archaea

In biology, the PYLIS downstream sequence (PYLIS: pyrrolysine insertion sequence) is a stem-loop structure that appears on some mRNA sequences. This structural motif was previously thought to cause the UAG (amber) stop codon to be translated to the amino acid 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.