Fig. 1.

ACE-2 receptor-mediated SARS-CoV-2 internalization occurs via three steps. The first step involves the recognition and attachment of the spike glycoprotein (SP, olive green) to its receptor ACE-2 (Red). This binding instigates the activation process wherein the spike protein is cleaved into its subunits, S1 (receptor-binding domain, light blue) and S2 (fusion peptide, yellow) via the adjacent transmembrane protease TMPRSS2 (light green). This fusion peptide integrates with the host cell membrane, resulting in subsequent release and internalization of the SARS-CoV-2 single-stranded RNA (ssRNA, blue) and other components. Once internalized, the virus utilizes the host cell machinery for replication and extrusion of novel viral particles (Colour, Double-column fitting image).