```The receptor binding domain (RBD) in the spike protein of SARS-CoV and SARS-related coronaviruses is the most variable part of the virus genome. Six residues in the RBD appear to be critical for binding to the human ACE2 receptor and determining host range1. Using coordinates based on the Urbani strain of SARS-CoV, they are Y442, L472, N479, D480, T487, and Y4911. The corresponding residues in SARS-CoV-2 are L455, F486, Q493, S494, N501, and Y505. Five of these six residues are mutated in SARS-CoV-2 compared to its most closely related virus, RaTG13 sampled from a Rhinolophus affinis bat, to which it is ~96% identical2 (Figure 1a). Based on modeling1 and biochemical experiments3,4, SARS-CoV-2 seems to have an RBD that may bind with high affinity to ACE2 from human, non-human primate, ferret, pig, and cat, as well as other species with high receptor homology1. In contrast, SARS-CoV-2 may bind less efficiently to ACE2 in other species associated with SARS-like viruses, including rodents and civets1. ``` http://virological.org/t/the-proximal-origin-of-sars-cov-2/398 make my stoinks go up even more <:hypersmugon:544638648721604608> !
