Fig. 2 Schematic representation of the human 2019-nCoV S-protein with a focus on the putative maturation sites. The domains were previously characterized in SARS-CoV and MERS-CoV: Signal peptide (SP), N-terminal domain (NTD), receptor-binding domain (RBD), fusion peptide (FP), internal fusion peptide (IFP), heptad repeat 1/2 (HR1/2), and the transmembrane domain (TM). The SP, S1↓S2 and S2′ cleavage sites are indicated by arrows. The sequence of different CoV S1/S2 and S2′ cleavage sites were aligned using Multalin webserver (http://multalin.toulouse.inra.fr/multalin/) with manual adjustments and the figure prepared using ESPript 3 (http://espript.ibcp.fr/ESPript/ESPript/) presenting the secondary structure of SARS-CoV S-protein at the bottom of the alignment (PDB 5X58) (Yuan et al., 2017). Insertion of furin like cleavage site is surrounded by a black frame. Red asterisks indicate the presence of a canonical furin-like cleavage motif at the S1/S2 site. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)