A BACTERIAL RNA THAT FUNCTIONS AS BOTH A TRANSFER-RNA AND AN MESSENGER-RNA

Bacterial tmRNA (transfer-messenger RNA, also known as 10Sa RNA) conta ins a tRNA-like structure in the 5'- and 3'-end sequences and an inter nal reading frame encoding a 'tag' peptide. The dual function of this molecule as both a tRNA and an mRNA facilitates a trans-translation re action, in which a ribosome can switch between translation of a trunca ted mRNA and the tmRNA's tag sequence. The result is a chimeric protei n with the tag peptide attached to the C terminus of the truncated pep tide.