This is one of 5 proteins that mediate the attachment of the 5S rRNA onto the large ribosomal subunit, where it forms part of the central protuberance and stabilizes the orientation of adjacent RNA domains. Part of the 50S ribosomal subunit. Interacts with proteins L5 and L21e, and attaches the 5S rRNA to the 23S rRNA. Has been cross-linked to L21e. Belongs to the universal ribosomal protein uL18 family.