tRNAGln and mutated proviral genomes. Panel A. Cloverleaf structure of tRNAGln,1 and tRNAGln,3. tRNAGln,1 (major) and tRNAGln,3 (minor) are depicted. The tRNAs differ in the nucleotides within the PBS (boxed) as well as nucleotides in the anticodon region (boxed). The modified nucleotides are noted. The structures are taken from Kuchino et al. . Panel B. Modifications in the NL-4 proviral genome. NL-4 WT refers to the wild type NL-4 genome with the PBS and A-loop complementary to tRNALys,3. NL-4-Gln1 refers to a modified proviral genome in which the PBS was modified to be complementary to the 3' terminal nucleotides of tRNAGln,1. NL-4 Gln1-AC also contains a PBS complementary to the 3' terminal nucleotides of tRNAGln,1 with additional modifications of the A-loop region (GAGTCAG) noted in bold. NL-4-Gln3 is an HIV-1 with the PBS modified to be complementary to the 3' terminal 18-nucleotides of tRNAGln,3. Note that the PBS is nearly identical with the exception of the T to C change in the PBS. NL-4 Gln3-AC refers to an HIV-1 in which the PBS was modified to be complementary to tRNAGln,3 with additional modification in the A-loop region consisting of GAGTCAA which is complementary to the anticodon region of tRNAGln3.