One of the early assembly proteins it binds 23S rRNA. One of the proteins that surrounds the polypeptide exit tunnel on the outside of the ribosome. Forms the main docking site for trigger factor binding to the ribosome. Part of the 50S ribosomal subunit. Contacts protein L29, and trigger factor when it is bound to the ribosome. Belongs to the universal ribosomal protein uL23 family.