Fig. 6.

Longitudinal (a) and transverse (b) views of frozen-hydrated tarantula thick 3D reconstruction, filtered to 2-nm resolution (EMD-1950) showing four IHMs helices (blue), packed tails (gray), and PM core (orange). The 3D reconstruction shows four 14.5-nm crowns, each with four IHMs. Densities of two IHMs (top) are shown, with blocked (BH, green) and free (FH, blue) heads and its subfragment 2 (S2, magenta). The model 3JBH (bottom), made from two adjacent IHMs models, shown as spheres, was flexibly fitted to the map. Blocked and free heads MHCIIs in green and blue, ELCs in magenta (FH) and orange (BH), and RLCs in red (FH) and yellow (BH). c Tarantula myosin II molecule based on 3JBH plus tail built with tarantula MHCII sequence (GenBank KT619079). d Tarantula pseudo-filament model built with tarantula myosin II molecules in (c)