Sequence complementarity of tRNAGln and tRNAThr with mutant proviral genomes. Panel A. Sequence complementary of tRNAGln,3 with NL-4-Gln3-AC. Depicted is the predicted complementarity between the 3' terminal nucleotides and the PBS and the anticodon of tRNAGln,3 with the modified A-loop region of NL-4-Gln3-AC. Panel B. Complementarity between 3' terminal nucleotides of tRNAThr with the PBS of NL4-Gln3-AC. Nucleotide differences within the PBS and tRNAThr are underlined. The anticodon region of tRNAThr has complementarity with the modified A-loop region of NL-4-Gln3. Additional complementarity between tRNAThr and the PBS of NL-4-Gln1-AC is also shown. The single nucleotide difference between the PBS is underlined. The resulting GC pair of tRNAThr and the PBS of NL-4-Gln3-AC should be compensated for by a GU base pair. Note also the predicted complementarity between the anticodon region of tRNAThr with the modified A-loop region of NL-4-Gln1-AC.