Fig. 1

PTC-RT process. a Ribosome encounters premature termination codon (PTC); the site is recognized by the translation termination machinery and the polypeptide elongation is prematurely terminated. b After addition of readthrough compound, translational machinery decodes PTC (PTC is recognized by nc- tRNAs), and translation continues until the normal termination codon (NTC). It allows translating a full-length protein. The NMD surveillance mechanism may detect and degrade PTC-bearing transcripts. If the NMD process is inhibited, very low levels of the full-length protein can be present even in the absence of stimulating agents, as the result of the endogeneous suppression of PTC