Identification of the 30 S protein adjacent to peptidyl transferase catalytic center of Escherichia coli ribosomes.

Iodoacetylphenylalanyl-tRNAPhe was used as an affinity label to localize the ribosomal components involved in the peptidyl transferase catalytic center of Escherichia coli ribosomes. When labeling was carried out at pH 5.0, the affinity label could specifically label the ribosomal components which comprise the catalytic center. Analysis of ribosomal proteins which had reacted with the affinity label revealed that a 30 S subunit protein, S 20, was located at or near to the ribosomal binding site of the 3'-terminus of aminoacyl- or peptidyl-tRNA.