Directly binds to 23S rRNA. Forms what is known as the L1 stalk, which protrudes beyond the 70S ribosome surface. The stalk is preferentially stabilized in 70S versus 50S crystals. Interacts with the E site tRNA, blocking the exit path. This blockage implies that this section of the ribosome must be able to move to release the deacetylated tRNA. Protein L1 is also a translational repressor protein, it controls the translation of the L11 operon by binding to its mRNA. Part of the 50S ribosomal subunit. Belongs to the universal ribosomal protein uL1 family.