Fig. 3.

(A) The structure of the spike protein model of COVID-19 in its homotrimer state (colored cartoon). Two chains, A (green) and B (cyan) are in the closed conformation, while chain C (magenta) is the open configuration that makes it able to recognize the host cell receptor. Region IV of the spike (C480-C488), which we suggest is the recognition site for cell-surface GRP78, is shown in the black cartoon in the enlarged panel. (B) The structure of the region III (black carton). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)