Fig. 3.

(A) The Cα-trace superposition of the model fitted based on the X-ray data (red) and the cryo-EM map (black) built based on the X-ray data (middle) and the cryo-EM map (right). Although there are minor perturbations in the map between Sac3 and Thp1, the overall structures are very similar and the “V”-shaped nature of the M-subcomplex is conserved. (B) Two views of the cryo-EM map fitted with the model built using the 3T5V crystal structure and poly-Ala helices for the additional density. (C) Comparisons of the two maps as boxed in panel B. It is clear that the region of Sac3 that was newly built (boxed in black) moves in the cryo-EM map relative to the X-ray map. Other helical features corresponding to Thp1 (boxed in red) and Sem1 (boxed in blue) agree well between the two maps.