AMINO-ACIDS AS RNA LIGANDS - A DIRECT-RNA-TEMPLATE THEORY FOR THE CODES ORIGIN

Numerous RNA binding sites for specific amino acids are now known, com ing predominantly from selection-amplification experiments. These site s are chemically discriminating despite being predominantly small, sim ple RNA structures: internal and bulge loops. Recent studies of sites for hydrophobic side chains suggest that there are other generalizable structural features which recur in hydrophobic RNA sites. Further, si tes for hydrophobic side chains can contain codons for the bound amino acid, as has also long been known for the polar amino acid arginine. Such findings are comprehensively reviewed, and the implications for t he origin of coded peptide synthesis are considered. An origins hypoth esis which accommodates all the data, DRT (direct RNA templating), is formulated.