The large subunit of the ribosome is an RNPzyme, wherein the RNA forms the active site, but proteins are critical co-factors (image courtesy of T. Cech). Proteins (also called polypeptides) are formed from chains of linked amino acids. As with nearly all biological processes that involve nucleic acids, base pairing interactions play a key role in the translation of genetic information from mRNA into protein. How do we know that basepairing is key?