The primary receptors involved in the entry of SARS-CoV-2. SARS-CoV-2 binds to the ACE2 receptor via the spike protein; specifically, ACE2 binds to the S1 subunit at the RBD (Receptor Binding Domain) level, TMPRSS promotes binding by interacting with the spike protein, while Furin detaches the bond between the S1 and S2 subunits, favoring the fusion of the virus capsid with the cytoplasmic membrane. ADAM17 is responsible for the shedding of the ACE2 receptor. (A) The virus penetrates cells through endocytosis, after binding with the ACE2 receptor, (B) forming an endosome where cathepsin L cleavage of the spike protein releases viral RNA.