L6 is a protein from the large (50S) subunit. In Escherichia coli, it is located in the aminoacyl-tRNA binding site of the peptidyltransferase centre, and is known to bind directly to 23S rRNA. The superfamily includes ribosomal proteins from several species, including L6 from bacteria, cyanelles (structures that perform similar functions to chloroplasts, but have structural and biochemical characteristics of Cyanobacteria) and mitochondria, as well as L9 from mammals, Drosophila, plants and yeast.

L6 contains two domains with almost identical folds, suggesting that is was derived by the duplication of an ancient RNA-binding protein gene. Analysis reveals several sites on the protein surface where interactions with other ribosome components may occur, the N terminus being involved in protein-protein interactions and the C-terminus containing possible RNA-binding sites. This alpha-beta domain found duplicated in ribosomal L6 proteins consists of two beta-sheets and one alpha-helix packed around single core.

PFAM:PF00347, INTERPRO:IPR036789,PMID:8262035