Fig. 1: The spike protein of SARS-CoV-2 drives infection.
From: Neutralizing nanobodies bind SARS-CoV-2 spike RBD and block interaction with ACE2
a, Schematic of the spike protein of SARS-CoV-2. The spike protein is composed of S1 and S2 subunits. S1 contains the RBD (highlighted in red). Using the RBD, the trimeric spike molecule binds to ACE2 on human cells (a single ACE2 is shown in blue). b, RBD residues that are shared between SARS-CoV-2 and SARS-CoV-1 are highlighted in cyan (SARS-CoV-2, top) or in light gray text (SARS-CoV-1, bottom). Residues that contact ACE2 are highlighted in red for each sequence. Other sequence differences are in black text, with conservative substitutions indicated by colons (:) underneath. Residues in contact with the H11-H4 nanobody are boxed. c, Camelids have antibodies that are dimers of a single chain. The constant region is in black and the variable region in yellow. When the VHH domain is expressed on its own, it is termed a nanobody. A topology diagram shows that the nanobody is composed of two β-sheets. Three loops—complementarity-determining region 1 (CDR1), CDR2 and CDR3—control antigen binding and are highlighted in purple.
