Visualization of ribosome--single-stranded DNA complexes in the electron microscope

A procedure is described which allows ribosomes bound to single-stranded DNA to be visualized in the electron microscope. The number of bound ribosomes may be determined and the position of the bound ribosomes may be readily measured along the DNA. The distribution of ribosomes bound to separated l and r strands of lambda DNA was shown to conform to the pattern predicted for binding at specific sites. The procedure should allow mapping of ribosome binding sites for the determination of genetic maps and may also be useful for studying translational control and relative binding affinities for ribosomes.