Figure 4.

The domain structure of ACE2 and collectrin. Both proteins are type I transmembrane glycoprotein with a signal peptide sequence (purple), a transmembrane domain (black) and a short C-terminal cytoplasmic domain. ACE2 has an extracellular amino-terminal catalytic domain with one zinc binding motif (HEXXH) (orange) corresponding to the active site of the enzyme. The carboxy-terminal cytoplasmic domain of ACE2 share 48% sequence homology with collectrin. The monoclonal anti-ACE2 antibody recognizes a predicted sequence in the N-terminal extracellular domain between Gln18 and Ser740, while the polyclonal antibody targets a precise sequence in the intracellular C-terminal domain corresponding to the 788-805 amino acids located within the homology region denoted by the green box.