Pyrrolysine

Definition

Pyrrolysine is a rare, naturally occurring amino acid that is used in the ribosomal synthesis of proteins in some archaea and bacteria. It is encoded by the UAG codon, which is normally a stop codon.

5 Must Know Facts For Your Next Test

1. Pyrrolysine is the 22nd genetically encoded amino acid.
2. It is incorporated into proteins by a unique tRNA and its corresponding synthetase.
3. The UAG codon, usually a stop signal, codes for pyrrolysine in certain organisms.
4. Pyrrolysine is involved in methane metabolism in methanogenic archaea.
5. It was first discovered in the archaeon Methanosarcina barkeri.

Related terms

Methanosarcina barkeri: An archaeon species where pyrrolysine was first discovered.

tRNA:

Transfer RNA; it helps decode mRNA sequences into proteins.

Selenocysteine: The 21st amino acid incorporated into proteins, similar to how pyrrolysine is added.