Together with proteins, ribosomal RNA forms the ribosomes, which play a structural role and also a role in ribosomal binding of messenger RNA (mrna) and transfer RNA (trna). The function of ribosomal RNA is to provide a mechanism for decoding mrna into amino acids and to interact with the trnas during translation by providing peptidyl transferase activity.The trna then brings the necessary amino acids corresponding to the appropriate mrna codon.