Tertiary structures of HIV-1 reverse transcriptase and chemical formulas of NRTIs and NNRTIs. (A) HIV-1 RT complexed with dsDNA and zidovudine triphosphate (left) (PDB accession number 3V4I) and nevirapine (right) (PDB accession number 4PUO). Tertiary structures of HIV-1 reverse transcriptase and chemical formulas of NRTIs and NNRTIs. (A) HIV-1 RT complexed with dsDNA and zidovudine triphosphate (left) (PDB accession number 3V4I) and nevirapine (right) (PDB accession number 4PUO). Two subunits of the HIV-1 RT heterodimer are shown in pink and orange, respectively. Zidovudine triphosphate targets the drug-binding pocket of NRTIs, known as the catalytic site, to inhibit the activity of HIV-1 RT during DNA synthesis. Nevirapine targets the drug-binding pocket of NNRTIs, known as the allosteric site, to block the activity of HIV-1 RT during DNA synthesis (see structural movies at http://www.virusface.com/). (B to H) Chemical formulas of zidovudine, stavudine, zalcitabine, emtricitabine, didanosine, lamivudine, and abacavir in the group of NRTIs. (I to M) Chemical formulas of delavirdine, nevirapine, efavirenz, rilpivirine, and etravirine in the group of NNRTIs. Erik De Clercq, and Guangdi Li Clin. Microbiol. Rev. 2016; doi:10.1128/CMR.00102-15