Cryo-EM structure of the SARS coronavirus spike glycoprotein in complex with its host cell receptor ACE2
(A) A size-exclusion chromatography elution profile of the low pH and trypsin treated S and ACE2 mixture. (B) Negative staining analysis of the S2 peak. Red arrows indicate rosette-shape structures formed by the post-fusion S2 trimers. Scale bar: 50 nm. (C) 2D class averaged cryo-EM images of the SARS-CoV S2 rosette. Scale bar: 10 nm. (D) 3D density map of the SARS-CoV S2 in post-fusion state with a fitted SARS-CoV S2 homology model. The three protomers are colored pink, yellow and cyan, respectively. Left: bottom view; right: side view.