This protein binds the 5S rRNA. It is required for the late stages of subunit assembly, and is essential for 5S rRNA assembly onto the ribosome. Part of the 50S ribosomal subunit (PubMed:340263, PubMed:3298242, PubMed:10094780, PubMed:12809609, PubMed:16272117, PubMed:25310980, PubMed:24844575, PubMed:27934701, PubMed:27906160, PubMed:27906161). Contacts the 5S rRNA (PubMed:3298242). Belongs to the universal ribosomal protein uL15 family.