Extended Data Fig. 4: Quality of the cryo-EM density for the core RTIC map.

a, View of HIV-1 RT from the front. The subdomains of RT are coloured. Underneath the main RTIC view, each subdomain of RT, plus the p51 subunit, is shown fit into the 4.5 Å map. b, View of HIV-1 RT from the polymerase active site side. The subdomains of RT are coloured. Underneath the main RTIC view, each subdomain of RT, plus the p51 subunit, is shown fit into the 4.5 Å map. In a, b, regions of protein, namely loops and linkers, that lacked sufficient density were removed after comparison with previously published structures of RT. These regions are indicated by dotted lines and are most commonly found in the finger and palm subdomains. c, Representative regions of 4.5 Å map fitted with protein secondary structure that display densities for side chains. A view of the PBS helix fit into the 4.5 Å map is also shown; phosphates of the RNA backbone are partially resolved. Regions are coloured with respect to the main text models.