 Phage-encoded tRNAs are believed to be insensitive to host anticodon nucleus activity due to mutations in the anticodons of the tRNAs. This is supported by the observation that phages tend to avoid encoding tRNAs with mutated anticodons, and that phage-encoded tRNAs are resistant to host anticodon nucleases. This article was authored by Dan F. van den Berg, Baltus A. van der Steen, Ana Rita Costa, and others.