Figure 4. Helical density in class 1 of the apo-state ensemble.
(A–C) Three different views of the map and the atomic model are shown. The kinked α-helix that is unaccounted for by the γ-secretase model is shown in purple. PS1 residues that interact with this helix are labeled.
Figure 4—figure supplement 1. Mass spectrometry and Western blot analyses.
(A) The lower part of a Coomassie blue-stained SDS-PAGE gel of the γ-secretase sample that was also used for cryo-EM imaging was cut out and submitted for mass spectrometric analysis. Besides known γ-secretase components (bold text), several proteins with a single predicted transmembrane helix were also identified. (B) Western blot analyses confirmed the presence of at least three of the identified proteins in the sample. Arrowheads indicate their expected molecular weights.