By two-dimensional gel electrophoresis, partial peptide mapping, and antibody binding we have shown that eukaryotic elongation factor Tu is in close contact with mRNA in rabbit reticulocytes. It can be crosslinked to mRNA by irradiating both polysomes and 40–80 S mRNA-protein complexes with short-wave UV light. To our knowledge this is the first case in which a known translation factor has been shown to be associated with mRNA in native ribonucleoproteins.
