Ribosome structure: localization of 3' end of RNA in small subunit by immunoelectronmicroscopy.

The 3' end of the RNA in the 30S ribosomal subunit of Escherichia coli has been modified by oxidation with sodium periodate and conjugation with the (mono) dinitrophenyl derivative of ethylenediamine. Antibodies, induced with dinitrophenyl-bovine serum albumin, interact with the modified ribosomal subunits. Electron micrographs of negatively stained antibody-subunit complexes show individual ribosomal subunits to which a single antibody molecule is bound and subunit dimers cross-linked by an IgG molecule. The modified 3' terminus has been localized to a single site on the upper portion of the platform region of the 30S subunit. This location is consistent with earlier placements of proteins that react with the 3' end of the RNA.