[Affinity labeling of ribosomes from Escherichia coli with 4-(N-2-chloroethyl-N-methylamino) benzyl-5'-phosphamides of oligouridylates of different length].

4-(N-2-chloroethyl-N-methylamino)benzyl-5'-phosphamides of tetra-, penta-, hexauridilates were used for localization of the proteins organizing the mRNA-binding centre of ribosomes from E. coli. These derivatives, alike oligonucleotides, stimulated the binding of phenylalanyl-tRNA to ribosomes. Within the specific ternary complex these derivatives alkylated both 30S and 50S ribosomal subunits with high efficiency. Tetradecauridylic acid protected ribosomal subunits from alkylation. In the 30S ribosomal subunit these derivatives modified 16S RNA and proteins S3, S4, S9, S11, S13, S14, S19. In the 50S subunit these derivatives alkylated 23S RNA and proteins L7/L12, L13, L23, L25, L32. It was found that oligouridylate derivatives of a different length modified different proteins. The data obtained in this paper indicate that the conformation of the ternary complex "70S.CIRCH2NHpU(pU)n-1.tRNAPhe", where tRNAPhe is bound only to P-site of the ribosome differs from the ternary complex where both A- and P-sites of the ribosome are occupied with tRNAPhe.