One of two assembly initiator proteins, it binds directly to the 5'-end of the 23S rRNA, where it nucleates assembly of the 50S subunit. It is not thought to be involved in the functions of the mature 50S subunit in vitro. One of the proteins that surrounds the polypeptide exit tunnel on the outside of the subunit. Part of the 50S ribosomal subunit (PubMed:391595, PubMed:10094780, PubMed:12809609, PubMed:16272117, PubMed:25310980, PubMed:24844575, PubMed:27934701, PubMed:27906160, PubMed:27906161). Might contact the SecYEG translocation complex when it is docked with the ribosome. Belongs to the universal ribosomal protein uL24 family.