L13 protein is one of the early assembly proteins of the 50S ribosomal subunit, although it is not seen to bind rRNA by itself. It is important during the early stages of 50S assembly (By similarity). L13 is part of the 50S ribosomal subunit. S9 is part of the 30S ribosomal subunit (By similarity). In the N-terminal section; belongs to the universal ribosomal protein uL13 family. In the C-terminal section; belongs to the universal ribosomal protein uS9 family. Given that these two proteins are not members of the same ribosomal subunit, and that they are not known to contact each other in the ribosome, this may be incorrectly predicted and should perhaps be two separate genes.