Fig. 1.

T4 lysozyme (T4L)β₂V₂R–βarr1 complexes formed and analyzed via EM with a newly developed functional purification method. (A) Schematic representation of the purification method to generate (T4L)β₂V₂R–βarr1 complexes. (B) Coomassie gel showing WT βarr1 interaction with (T4L)β₂V₂R in the absence or presence of conformation-stabilizing antibodies (Fab30, Nb32). IP, immunoprecipitation. (C) Representative negative-stain raw EM image of (T4L)β₂V₂R–βarr1–Fab30 complexes. (D) Class averages of the (T4L)β₂V₂R–βarr1–Fab30 complexes (Top) and (T4L)β₂V₂R–βarr1–Fab30–Nb32 complexes (Bottom) from negative-stain EM classification analysis. (E) Representative class averages (with cartoon representations) of the (T4L)β₂V₂R–βarr1–Fab30 complex in the tail and core conformations. (Scale bars: C, 20 nm; D and E, 10 nm.) (F) Summarized results of the different βarr1 FLR constructs tested for their ability to form the (T4L)β₂V₂R–βarr1–Fab30 core conformation in the presence or absence of Nb32. Note that the tail conformation encompasses all those (T4L)β₂V₂R–βarr1 complexes that are not in the core conformation.