Affinity labeling of peptidyl transferase center using the 3' terminal pentanucleotide from amino acyl-tRNA

Affinity labeling of proteins in the peptidyl transferase center of eukaryotic ribosomes can be carried out using as a probe p-nitrophenylcarbamyl-amino acyl-tRNA. However, when the reactive p-nitrophenylcarbamyl group is in the amino terminal of the 3' end pentanucleotide derived from amino acyl-tRNA by ribonuclease T1, covalent binding does not take place. An interpretation of the results suggests that the 3' terminal fragment binds to an RNA rich part of the ribosome, which probably forms the P-site in the peptidyl transferase center.