Ribosomal L18/L5e: L18 (L5e) is a ribosomal protein found in the central protuberance (CP) of the large subunit. L18 binds 5S rRNA and induces a conformational change that stimulates the binding of L5 to 5S rRNA. Association of 5S rRNA with 23S rRNA depends on the binding of L18 and L5 to 5S rRNA. L18/L5e is generally described as L18 in prokaryotes and archaea, and as L5e (or L5) in eukaryotes. In bacteria, the CP proteins L5, L18, and L25 are required for the ribosome to incorporate 5S rRNA into the large subunit, one of the last steps in ribosome assembly. In archaea, both L18 and L5 bind 5S rRNA; in eukaryotes, only the L18 homolog (L5e) binds 5S rRNA but a homolog to L5 is also identified.
Comment:In bacteria, incorporation of 5S rRNA into the large subunit depends on the presence of L18, L5 and L25, and is one of the last steps in ribosome assembly. Both L18 and L5 are present and bind 5S rRNA in archaea. In eukaryotes, only the L18 homolog (L5e) binds 5S rRNA, but a homolog to prokaryotic/archaeal L5 is also identified in the ribosomal large subunit.
Jiyao W et al.(2023). "The conserved domain database in 2023.",