This protein binds specifically to 23S rRNA; its binding is stimulated by other ribosomal proteins, e.g. L4, L17, and L20. It is important during the early stages of 50S assembly. It makes multiple contacts with different domains of the 23S rRNA in the assembled 50S subunit and ribosome (By similarity). The globular domain of the protein is located by the polypeptide exit tunnel on the outside of the subunit while an extended beta-hairpin forms part of the wall of the tunnel. Forms a pair of 'tweezers' with L32 that hold together two different domains of the 23S rRNA. Interacts with the tunnel-blocking modified macrolide azithromycin. Upon binding of the macrolide troleadomycin to the ribosome, the tip of the beta-hairpin is displaced, which severely restricts the tunnel. This and experiments in E.coli have led to the suggestion that it is part of the gating mechanism involved in translation arrest in the absence of the protein export system. Part of the 50S ribosomal subunit. Contacts protein L32. Belongs to the universal ribosomal protein uL22 family.