Biopolymers and cell. 1987. Volume 3. № 3. 157 - 160

M. V. Rodnina, Yu. P. Semenkov

THE NUMBER OF tRNA-BINDING SITES ON SOS RIBOSOMES AND THEIR SUBUNITS

Summary

    The ability of the rabbit liver ribosomes and their subunits to form complexes with different types of tRNAphe has been studied by the nitrocellulose membrane filtration technique. 8OS ribosomes are shown to have two binding sites for aminoacyl- or peptidyl-tRNA, but three binding sites for non-acylated tRNA. The third (E) site of 80S ribosome is formed by its 60S subunit. The number of tRNA binding sites on SOS ribosomes or 40S subunits is constant at different Mg2+ concentrations (5-20 mM). The analysis of I/v2 vs. 1/C plot or Scatchard plot indicates thai binding of AcPhe-tRNAPhe to ribosomes is of a cooperative process. 60S subunit is shown to have one codon-independent binding site specific for non-acylated tRNA.