Structure of mouse coronavirus spike protein complexed with receptor reveals mechanism for viral entry
Fig 5
Negative-stain EM image of MHV spike treated with protease in the presence or absence of CEACAM1a.
(A) MHV S-e without any protease treatment. All of the S-e molecules were in the pre-fusion state. (B) MHV S-e treated with low concentration of trypsin. All of the S-e molecules were in the pre-fusion state. (C) MHV S-e treated with high concentration of trypsin. 11.75% of the S-e molecules were in the post-fusion conformation (featured by the rod-like structure). (D) MHV S-e treated with low concentration of trypsin and incubated with CECAAM1a. All of the S-e molecules were in the pre-fusion state. (E) MHV S-e treated with low concentration of trypsin and incubated with urea. All of the S-e molecules were in the post-fusion state. (F) MHV S-e treated with high concentration of trypsin and incubated with CEACAM1a. 50.9% of the S-e molecules were in the post-fusion conformation. 2D averages of the S-e particles were shown as insets of each panel.