The importance of Escherichia coli ribosomal proteins L1, L11 and L16 for the association of ribosomal subunits and the formation of the 70-S initiation complex.

50-S subunits were washed with LiCl solutions of different concentrations. After washing with 1 M LiCl solution the particles lost their ability to attach either to 30-S subunits or to the AUG - 30-S subunit - fMet-tRNAfMet complex or to a poly(U) - 30-S subunit - Phe-tRNAPhe complex. Those proteins which were removed by LiCl were fractionated on a Sephadex G-100 column. Of the fractionated proteins only the combinations L1 and L11 or L1 and L16 were essential for the association of 50-S 1.0 cores (particles prepared by washing 50-S subunits in 1.0 M LiCl) with 30-S subunits. These three proteins were also required for the formation of a stable complex between 50-S 1.0 cores, mRNA, 30-S subunits and aminoacyl-tRNA.