Fig. 2.

Surface and ribbon representations of the tertiary structure of the S1 and S2 subunits of SARS_CoV S glycoprotein. In the S1 representation (left) the residues forming the hydrophobic cluster are highlighted. In red, green, and yellow the I, II, and III domains of the S2 subunit are, respectively, shown (right), together with the putative CD13 binding regions. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this paper.)