Figure 1.  First-generation NNRTIs bind to RT in a similar way.  Although first-generation NNRTIs have different chemical structures, they bind to RT in a "butterfly" mode with two hydrophobic wings at an angle of approximately 110°.  The position of the NNRTI binding pocket is shown on the upper right; a close-up comparing the binding of three NNRTIs, TIBO, alpha-APA, and nevirapine is shown on the left.  The side chains of the amino acids that make up the NNRTI binding pocket are shown in blue.  The majority of the pocket is derived from p66 (backbone in red); however, a small portion of the pocket is derived from p51 (backbone in blue). The side chain of E138 from the p51 subunit is shown in gold.