Requirements for the initiation of polyphenylalanine synthesis by recombined ribosomal subunits from yeast

摘要

A reaction stimulated by elongation factor 2 (EF-2) is necessary for the formation of the initial peptide-bond in poly(U)-directed peptide synthesis on yeast ribosomal subunits. The stimulation is inhibited by fusidic acid or diphtheria toxin together with NAD. It is assumed that the reaction of EF-2 represents translocation: in the presence of EF-2 almost twice the amount of N-acetyl-phenylalanyl-tRNA is bound to ribosomes and moreover, upon addition of puromycin a considerable stimulation of N-acetyl-phenylalanyl-puromycin formation is found. Contradictory data in the literature on this subject may be due to nonenzymatic translocation caused by a high monovalent cation concentration in the ribosome preparations or to an unspecific method for the extraction of N-acetyl-phenylalanyl-puromycin.