English: Three-dimensional morphing of the SARS spike, and ACE2 bound structures. This movie supplements Figs. 1, 3 showing the putative structural re-arrangement of the spike as it binds to ACE2. The movie starts showing the SARS spike and then gradually morphs to the SARS spike-ACE2 complex, and back to the SARS spike. The morphing reconstruction is shown from the side and end-on perspectives, and the mass attributed to the nucleocapsid is presented without morphing. As one watches the move play back and forth (this can be done by selecting “loop” in a QuickTime Player) one can see the spike twist by ∼5o when viewed from the end-on perspective, and the spike becomes squatter by ∼10 Å when viewed from the side perspective. The following color scheme was used: cryo-EM surface; ACE2, violet; spike, green; stalk, blue; envelope, beige; nucleocapsid, red.