Ribosomal Binding of AUG by Formyl-methionyl-sRNA

Abstract

IT has been shown that a triplet can facilitate the binding of an amino acyl-sRNA molecule to a ribosome¹, and, conversely, that an sRNA molecule can bind a labelled triplet to a ribosome². Recently, Kondo et al.³ have shown that, in the presence of the necessary components, formyl-methionyl-sRNA_F is required to bind the f2 phage RNA to 70S ribosomes at 5 mM Mg⁺⁺. In this communication we describe how labelled pApUpG can be bound in a stable complex to ribosomes in the presence of formyl-methionyl-sRNA_F, there being one molecule of triplet bound per molecule of sRNA bound. When puromycin is added, the formyl-methionyl residue is rapidly removed and the labelled triplet is more slowly lost from the ribosome.