This protein binds to 23S rRNA in the presence of protein L20 (By similarity). MYAVFQSGGKQHRVSEGQTIRLEKLDIATGETIEFDQVLMIANGEEINIGAPLVDGGKIKAEIIAHGRGEKIKIVKFRRRKHYRKQQGHRQWFTDVKITGISA 50S ribosomal protein L21 rplU RL21_YERPS YPTB0464 103