Caption (A) Schematic representation of SARS-CoV-2, the viral spike protein and the cleavage sites for furin (green, S1/S2 position; the cleavage sequence is shown below the protein structure) and ...

The SARS-CoV-2 spike or fusion protein is a trimer: a group of three units, each consisting of a receptor-binding subunit, S1, and a subunit responsible for fusion, S2. The three S1 and S2 ...