Fig. 1.

Puromycin structure and mechanism of action. (A) Chemical structures of the 3′ end of an aminoacylated tyrosyl-tRNA (left) and puromycin (right). The different bonds between the nucleoside and amino acid moieties are shown in pink. (B) Basic mechanism of puromycin action. During translation elongation, aa-tRNA enters the A-site and accepts the nascent polypeptide chain from the peptidyl-tRNA in the P-site. Following translocation, the A-site becomes available to accommodate the next aa-tRNA (top). Like aa-tRNA, puromycin can enter the A-site and accept the nascent chain. This results in translation termination, ribosome disassembly and release of the nascent chain bearing a 3′ puromycin (bottom). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)