Fig. 1.

Overview of currently known spike protein (S-protein) binding domains for diverse human coronaviruses. Schematic representation of coronavirus spike proteins drawn to scale. Orange boxes indicate signal peptides. Blue boxes indicate the N-terminal regions in α- and β-coronavirus spike proteins, which were mapped based on sequence homology between viruses within the same genus. Green boxes indicate known receptor-binding domains (RBD) in the C-terminal region of S1. Known receptors are indicated in the boxes: APN, aminopeptidase N; ACE2, angiotensin-converting enzyme 2; O-ac Sia, O-acetylated sialic acid; DPP4, dipeptidyl peptidase-4. Red boxes indicate transmembrane domains. Spike proteins are shown for Human CoV NL63 (GB: YP_003767.1), Human CoV 229E strain inf-1 (GB:NP_073551.1), HCoV-OC43 strain Paris (GB: AAT84362), HCoV-HKU1 (GB: AAT98580), SARS-CoV strain Urbani (GB: AAP13441), MERS-CoV strain EMC/2012 (GB: YP_009047204), SARS-CoV-2 strain (GB: AAP13441)