Three-dimensional reconstruction and averaging of 30 S ribosomal subunits of Escherichia coli from electron micrographs.

From the micrographs of a tilt series, several particles of negatively stained 30 S ribosomal subunits of Escherichia coli were three-dimensionally reconstructed. Three of them showing similar orientation with respect to the supporting foil were averaged after alignment by newly developed three-dimensional correlation methods. As a main result we found a stained channel-like structure inside the particle. We tentatively propose that this corresponds, at least partially, to positively stained segments of the 16 S RNA.